Multi-channel amplifier with a good dac. Fostex HP-A8mk2 High Quality USB DAC with Headphone Amplifier: A successful upgrade of the Fostex HP-A8C. years of innovation in sound

Ideal for playing FLAC, WAV, Apple Lossless and other compression formats without quality loss.

The Topping TP32EX uses a Tripath TK2050 class T digital amplifier, delivering 50W per channel. Massive gold-plated speaker terminals can handle even the thickest speaker cables. Separate headphone output so as not to disturb the neighbors at night, or it can be used to connect a subwoofer.

Order delivery of the amplifier in black or silver, the Topping TP32EX is ideal for organization of high-quality sound on the computer.

Compact dimensions and high power output

The amplifier circuitry is based on Tripath's TK2050 power amplification module. Due to the high efficiency of these modules (about 90%), the amplifier turned out to be compact and with a high output power comparable to full-size counterparts.

Wide connectivity options

Despite its modest size, the Topping TP32EX has all the audio I/O you would expect from a device specifically designed for use with a computer or netbook, including 1 digital input (coaxial), 1 analog line input, and a USB port for fast and convenient connection to a computer. Cables or BANANA connectors can be used with acoustic output terminals. The 6.3mm port can be used to connect a subwoofer. The headphone output will be useful at night, in the office, or in other situations where loud sound can disturb people around.

Cirrus Logic CS4392 DAC and adaptive USB interface

The TP32EX uses the built-in Cirrus Logic CS4392 DAC to convert digital signals. No need to install drivers on Windows or Mac, just connect the machine to your computer with a USB cable. You can then use iTunes, Foobar, or another software player to play your music. The technical characteristics of the amplifier will satisfy the most fastidious audiophile who prefers sources with a resolution of up to 24bit / 192kHz. The adaptive USB interface is currently the best in terms of price / quality ratio, and taking into account the high-quality circuitry in this device, it often outperforms a low-quality DAC with asynchronous USB.

Size doesn't matter

Not every full-sized device has a CS3310-based digital volume control, remote control and aluminum front panel, but here it is. Screw-type acoustic terminals, display and selectors are the same as on large devices. All this gives the utmost ease of use and connection of the device.

No fans in the case - complete silence

All efforts to reduce the noise in the audio signal are worth nothing compared to the annoying noise of the cooling fan in the amplifier case. In order to achieve high output power in a compact size and at the same time noiselessness, the cooling radiators are placed on the chassis in a special way for efficient heat dissipation without additional fans.

3 output modes

The device has a completely separate power amplifier and headphone amplifier. They can work both one by one and simultaneously. Thus, there are 3 modes of operation: speaker amplifier, headphone amplifier, simultaneous operation of amplifiers. In the third mode, you can connect, for example, a subwoofer to the headphone jack. In headphone amplifier mode, you can also use the unit as a preamplifier or a dedicated DAC.

Specifications

And now I have comprehended the secret of music, I understood why it is head and shoulders above all other arts: the point is its incorporeality. As soon as she is separated from the instrument, she belongs to herself again. She is an independent sum of sounds, weightless, incorporeal, utterly pure and in perfect harmony with the universe.

Walter Moers. "City of Dreaming Books"

Most people perceive the sound reproduced by the devices that accompany us every day - a laptop, smartphone, headphones or speaker system - as the final product. Without thinking about the fact that this sound can be improved, to make it truly "live", rich and beautiful. Music should inspire, delight, bring a sense of calm or energize - depending on the musical preferences and mood of the listener. But before talking about improving the sound, it is worth understanding the technical side of the issue. The two technical devices responsible for sound quality are the DAC and the amplifier.

Modern DAC from the inside

First you need to understand what a DAC is. This is a digital-to-analog converter, that is, a device that converts a digital signal into analog sound. Computer hard drives and audio discs store material digitally, while speakers and headphones reproduce sound from an analog signal. Therefore, somewhere between the storage medium and the final playback device, a digital-to-analog conversion must occur, that is, the conversion of zeros and ones into electrical impulses. It can occur in sound cards, in players, in receivers or in mp3 players, because all these devices just have a built-in DAC chip. The quality of the analog audio signal received at the output depends both on the DAC chip used and on other technologies involved in the process, as well as on many other factors, among which high-quality power supply and the device circuit itself are important. In other words, we can say that the DAC is the "brain" of any audio path. D/A conversion differences are one of the reasons why some devices sound better or worse than others.

External D/A converters tend to reproduce sound more accurately than the DAC found in sound cards, budget receivers and players because they are specialized devices. DACs are convenient in that they can be connected to any device that has a digital output, and most DACs can also be connected via USB. Purchasing a quality external DAC can greatly improve the sound quality of your system.

Now it's worth talking about another device that directly affects the sound quality - an amplifier.

Fosgate Signature Tube Amplifier

Many are interested in what separate headphone amplifiers are for. After all, almost any sound card, laptop, player or mp3 player has a headphone output, when connected to which the headphones work - without any amplifier. In fact, headphones are able to work with all of these devices precisely because most of these devices already have an amplifying part in their composition before going to the headphones. Thus, it is wrong to assume that someone uses headphones without an amplifier, just that many use the one provided in their sound source as an amplifier. What are the advantages of a separate amplifier?

It is believed that the purpose of any amplifier is to amplify the sound signal received from the source without changing its structure, that is, without introducing anything of its own into the sound. In reality, however, different amplifiers sound different with the same equipment, at the same volume level. Similarly, headphones sound different with different amplifiers, although the degree of this difference can vary greatly depending on individual headphones and amplifiers. However, the difference between a very good and a very bad amplifier is clearly audible on most headphones, and the most common representatives of very bad headphone amplifiers are just the outputs of most budget players, sound cards, players and phones. In other words, buying a separate quality headphone amp will always bring out the best sound from your existing headphones. By increasing the current strength in the amplifier, the detail and atmosphere of the sound is increased. This important factor plays an important role when listening to music, since a large amount of material in compositions is recorded at a very low volume level (the so-called overtones, reverberations, etc.) and they can only be heard normally with the help of an amplifier. Buying a separate amplifier is often a more worthwhile investment than upgrading to more advanced headphones. In addition, there are also headphones that are especially demanding for amplification, which, without a good amplifier, in principle, show a very small part of their real capabilities, mainly for high-impedance headphones (or any headphones paired with a weak player/smartphone amplifier). It is recommended that you listen to the desired headphones with various amplifiers before buying in order to understand what kind of sound they are capable of producing and what level of amplification you need to count on.

All participants of today's testing are distinguished by small dimensions and the ability to work autonomously from the built-in powerful battery. Thus, the devices are primarily designed for use with smartphones and portable players. However, nothing prevents you from using them with a desktop computer and a laptop - after all, the built-in headphone amplifier is able to cope not only with portable headphone models, but also with full-size ones, and even with very low sensitivity. Moreover, a dedicated line output allows you to connect active speakers in addition to headphones. So, when we say "USB DAC for mobile devices", let's not forget that these are truly universal devices. The scope of their application is very wide and clearly goes beyond the “listen to music on the road” option. For example, three out of six participants have an advanced proprietary ASIO driver, and two of them have the ability to play PCM up to 384 kHz and DSD. Such capabilities bring them to the level of traditional external USB DACs.

What is the difference from the overall stationary DAC? The point is mainly in minor inconveniences: all input-output connectors are only minijack format, there is no screen. But the digital inputs and outputs of S / PDIF, inherent in the "large" devices, are preserved.

Let's take a closer look at the participants.

Creative Sound Blaster E5

This is the new, most advanced model of the manufacturer, with a 4-core DSP processor on board, with a hardware equalizer and a ton of Creative processing. When connected to a computer, Sound Blaster E5 turns into a full-fledged sound card with ADC, drivers, internal mixer, headset input, line-in and everything else. When connected to a smartphone or tablet, this is a full-fledged USB DAC with a battery inside. There is a dedicated full-size USB input for iOS/Android devices. Micro-USB - only for the computer and recharging the battery. There is also Bluetooth for wireless use, for example as a headset - microphones are built into the card. For iOS/Android, there is a special application that manages all the settings of the internal processor from a mobile phone.

No one expected miracles from this Creative card - inexpensive (MSRP $200), with a very controversial design, a bunch of SBX Pro Studio processing that no other studio has heard of. We are already tired of criticizing Creative for striving to “cram everything and more” to satisfy all users at once. The result is a harvester that can't really do anything well. Users who need a lot of features and do not care about sound quality are not ready to pay a high price for a card. And those who are willing to pay, require first of all the sound quality, considering everything else as a free bonus.

In fact, it turned out that the Sound Blaster E5 is a completely new development, which has nothing in common with all previous budget Creative USB cards and is fundamentally different from the younger E1 and E3 models. In the new map E5 in the only one, everything is done the way we would like. There is normal direct support from 44.1 to 192 kHz and surprisingly great stuffing:

• Cirrus Logic CS4398 DAC
• ADC Cirrus Logic CS5361
• Texas Instruments TPA6120A2 Headphone Amplifier

It is clear that even a good filling is not a guarantee of quality. However, in comparison with the pretty good new E3 card, not to mention all the previous Omni, etc., the older E5 model played much better! The drivers are much better designed, there is a special Direct Mode that explicitly disables all processing, the ASIO driver supports all frequencies and works correctly. The map is designed very carefully and inspires great hope. (In large part this was the result of our constant pressure on Creative, relying on readers and quoting their opinions from our forum.) Among the unique features of the E5 are two headphone outputs, a microphone array of three built-in microphones with a position sensor, included holder for mounting on a microphone stand. Still, Creative's marketing could not resist and stuffed everything into the card, to the very eyeballs.

Note that the E5 has a relatively bulky case, a volume control without notches, and it is impossible to connect Android devices via Micro-USB. But the affordable price and outstanding sound for many will outweigh these small flaws and Singaporean marketing quirks. On the whole, the strongest competitor on the market for both USB sound cards and mobile USB DACs turned out quite unexpectedly.

Oppo HA-2

The Oppo developers were able to surprise with a stunning design and the most intriguing stuffing: the ESS Sabre32 9018 DAC in its 2M mobile version. This looks quite natural, since the Oppo HA-1 stationary DAC is based on the original ESS Sabre32 9018 for Hi-End component devices. This microcircuit has today record signal / noise and Kr characteristics, surpassing all other DAC microcircuits by a wide margin. Other manufacturers rarely use 9018, as it is very expensive and requires a lot of experience in its "cooking" (Chinese homemade kits from eBay for some reason "do not sound"). Another bonus from using Sabre32 is PCM support up to 384 kHz and DSD64/128/256. Oppo developers also provided ASIO drivers with the ability to put a very large buffer up to 8192 samples and select a high priority for transferring the USB stream in the system.

Thus, the Oppo HA-2 USB DAC has been very carefully designed and prepared for the most demanding and advanced users. The only drawback is probably not the most affordable price. But Oppo HA-2 is the thinnest external DAC among all participants. He factor of thinner than others, and even despite the additional non-removable leather cover! Body material - aluminum, all-metal body. As in the case with Creative, we had a pre-production sample provided by the manufacturer for testing. According to Oppo, an updated version will go into the series, with even more improved sound quality and increased power reserve of the amplifier.

Denon DA-10

The DAC is based on the TI PCM1795, a favorite of the Japanese from Denon. This 32-bit converter can play PCM up to 192kHz and even DSD64/128. It is stated that digital filtering is performed using a special proprietary technology AL32 advanced DSP. But most of all, we were struck by the giant two-piece leather case in the kit, which is designed to carry both the DAC and the smartphone at the same time.

The device is made of plastic with decorative aluminum plates and a handle. The body is made thick on purpose - to make it convenient to turn the volume knob in the sound card mode. The Denon DA-10 is very well made, comes with an ASIO driver and is not cheap. It feels like a very high-end device, designed to compete with the most expensive models without sinking into the mass market. The kit even comes with wires for iOS devices - both with a Lightning connector and a 30-pin one. Everything looks very well thought out.

FiiO E18 Kunlun

The Chinese DAC FiiO with the patriotic prefix Kunlun (Mountains of the Moon, the largest mountain system in China) contrasts with the previous participant with its affordability and democracy. There is no ASIO driver, no iPhone connector. The E18 Kunlun is designed for use with Android devices only and allows you to connect very simply with a miniature Micro-USB-Micro-USB cable. It also connects to a PC, after which it immediately starts working without requiring drivers. However, there is a trick: the device is seen in the system as a digital S / PDIF output, as if hinting to the OS that the mixer transmits data bit by bit, without multiplying or dividing the digital stream in the mixer and without mixing anything into the result.

The design of the device is chic - everything is completely metal, miniature. We note an additional Micro-USB for charging, different from the interface Micro-USB for pairing devices. This is one of the very few DACs that has a choice of modes: PC, Phone, Charge Out (PC sound card, external DAC for Android and just recharging the phone battery). Unlike many FiiO DACs, this is not a WM8740, but a TI PCM1798. Volume control - Alps. This is the second reincarnation of the device, with minor improvements. For its low cost, the DAC looks like a work of art - a very formidable rival in the budget category.

Tento Porta D.A.C. 1866

The German-made Tento Porta DAC 1866 has a radically different ideology. This product was the pinnacle of a long journey of adherents of orthodox R-2R DACs, such as the Analog Devices AD1866 used here. This DAC only works in 16bit 44kHz mode, but that's exactly what fans of various homemade devices with exotic stuffing need. There is a theory circulating on the Internet that the “golden age” of the digital has ended with the advent of low-bit converters with oversampling. They say that the soul of sound recording is lost behind high technical characteristics. Actually, for a long time it was like that: the first 1-bit converters played just awful. Now the situation is not at all so unambiguous, no matter what some anarchically minded leaders of specialized forums may say.

So, this Tento DAC is designed for those who collect non-standard products and are nostalgic for the good old days. From the trends of progress, there are Mini-USB and Bluetooth interfaces. However, there is also an optical/coaxial S/PDIF and an unregulated line output. The kit comes with very good quality cables, and the foam packaging even touched us. There is only one minus of the device - the price is not so small as to just buy it for your collection. This is probably a fee for manual work and production in Germany.

Venture Craft Go DAP BXD

The Japanese from Venture Craft outdid everyone else with pretentiousness. This is the case when we, who have seen a lot of things, could not stand it and fainted. Starting from the instructions only in Japanese and ending with the lack of a DAC mode via the USB bus, despite the fact that the Micro-USB connector is present! However, you are required to connect only via optical or coaxial.

This is the only DAC on a very strange PCM5100A converter, but with a Muse 8920 in the preamp! You will be surprised, but the kit even comes with printed circuit boards for adjusting the damping factor of a balanced amplifier (!) with a 2.5 mm microjack connector (an adapter is purchased separately). The product is clearly for "monsieurs who know a lot about perversions." However, the headphone amplifier is an old friend, MAX97220A, which has proven itself very well in well-known products.

The numbers of the passport characteristics of the device look strange. If the impedance of 8-600 ohms shocks with its range, then the quality is below any shabby integrated sound: 95 dB S/N, 0.01% distortion. We hasten to please: this is a self-incrimination of the manufacturer. Our measurement numbers are much better: 100 dB S/N and 0.002% distortion at any load.

In total: a nice, but very strange, in our European opinion, device, all settings of which are regulated by opening the case and rearranging jumpers and miniature printed circuit boards. One gets the impression that this is not a USB DAC, but some kind of “tamagotchi for an audiophile”. Our wish to the manufacturer: to think over the same replacement on miniature boards of the block with a DAC chip, and also to revive the work via USB. It doesn’t look as cool as a sandwich of three devices (namely, such an example is shown on the manufacturer’s website), but it’s convenient!

Headphones

For our testing, we specifically selected headphones that would fit the typical use of high-end mobile DACs.

As in-ear headphones (IEM, “plugs”), we tried Grado GR10 (20 thousand rubles), Fisher Audio TBA04 (10 thousand rubles), Sennheiser IE-8i (12 thousand rubles), Creative Aurvana in-Ear3 (6 thousand rubles).

We ended up using a Grado GR10 (32 ohms, 116 dB/mW) and a Sennheiser IE-8i (16 ohms). These small headphones retain the signature sound of their larger brothers. Very interesting models worthy of a good quality DAC. Fisher Audio and Creative have some work to do.

Grado RS1e (35 thousand rubles) - excellent, very smooth headphones. The 32 ohm impedance makes them listenable even without a preamp, or conversely saves the amplifier's battery life. The only feature is overhead (supra-aural) headphones, with a clamp directly to the ears. For extended listening it is better to loosen the headband. The sound is traditional for the classic Grado series, very comfortable. Perhaps there is a small overpayment for the mahogany in the design.

Grado SR325is (14 thousand rubles) - a more modern version, closer in sound to the Professional series. The cups are made of aluminum, which hints at a more "folk" model. Headphones just hit us on the spot with detail in the midrange. The difference between the tested DACs manifested itself, perhaps, most clearly. Grado SR325is play much more expensive than their price. After testing, we even bought this model for our personal use. There are also disadvantages: the sound is rougher than in the Reference series. We definitely recommend listening!

Audio-Technica ATH-M50x (9 thousand rubles) is a very popular model with a well-balanced sound and detail throughout the entire range. One of the best foldable headphones, and the emphasis on the lows will come in handy on the road. The 38 ohm impedance makes them suitable for connecting directly to a smartphone, but there is a benefit to a separate amplifier, and no small one.

Beyerdynamic DT 1350 (16 thousand rubles) - a novelty of the Tesla series, especially for portable equipment, with a cord shortened to 1.5 m. A very strange model with a weak impact on bass. On the Internet, reviews are divided into two equal categories: “didn’t understand what it was” and “very even, unadorned sound, I’m satisfied.” We obviously fall into the first category, but we do not rule out that there will be fans of this sound as well.

Test Methodology

We connected all 6 devices to one computer at the same time. 6 portable copies of foobar2000 were created. A test composition was launched, a comfortable volume level was set. Further, using the RMAA program, we set the same volume for all devices with headphones connected to eliminate the effect of voltage drop from the load. The volume of all devices was set with an accuracy of 0.1 dB.

This is very important, since even the same tested device with a difference in the volume of a phonogram of only tenths of a dB can be perceived as higher quality in the case of a louder version. When playing the same file! Subjectively, it will seem that there are more details, a little better bass, attack, and so on. That is, in fact, the device "loses to itself", which is completely unacceptable for a proper examination. Clearly, when compared with a deliberately bad device, these measures look like reinsurance, but when comparing audio paths of the same class, such requirements are mandatory. Andrey Subbotin, a world-class expert in the field of mastering, warned about this all the time. With regard to the preparation of phonograms, he always demanded to compare only mastered versions of the phonogram equalized in volume. Comparing anything at different volumes is a path to self-deception, as the louder option is for human hearing always will sound a little better. Everyone can easily verify this.

sound

The examination took several days. We understand the importance of this comparison and our responsibility to readers. Anyone can check the results for themselves - and we are sure they will come to the same conclusions. We even specially attracted two independent experts to once again make sure that the assessments of all trained students are similar. There may be only small nuances in the interpretation of terms, but not in the global assessment of sound quality.

Determining the scope of our scale, we took two devices: the integrated sound of a modern laptop (Realtek ALC282 audio codec) and the Lynx Aurora 8 rack studio interface. Realtek sound features: there are no obvious distortions or sound defects, but there is no detail either. All tracks play synthetically, with a very flat stereo pan, no reverb tails. Speaking in audiophile language, the sound is clamped, lifeless, it is very unpleasant to listen to it for a long time. The interface of the top-tier Lynx Aurora 8 is the complete opposite. It is impossible to break away from the music. The stereo panorama goes far beyond the room, but not due to artificial effects, but thanks to the high detail, very clean and tight mids, the reverb of each instrument in the mix is ​​well heard individually. Modern phonograms with a very strong volume maximization do not overload the sound path, their distortions mysteriously become barely noticeable and do not interfere. All claims and arguments about the “soulless digital” disappear in an incomprehensible way, everything good that you expect from a recording becomes audible in the sound, and nothing distracts from the perception of music. This is what the ideal path should be. Of course, questions remain with the interpretation of timbres and with absolute reference. For example, it is often the case that one device has cleaner high frequencies, but is less preferred in terms of sound in some other range. But before this problem of very subtle nuances, low-cost devices still need to grow very long and hard.

So, in comparison with the integrated sound of a laptop and even with the sound of a good codec of the Samsung Note 3 phone, any of the tested USB DACs plays an order of magnitude better. And the better the headphones or speakers play, the better the difference is heard, the more new details appear in the sound. So, there is even a sense in acquiring these devices, but only for owners of a normal sound path. Not necessarily Hi-End, but successful models of Hi-Fi equipment or studio monitors are a necessary minimum.

We sorted the test participants according to the places of the quality hit parade.

The Venture Craft Go DAP BXD sounds nice and smooth, but this DAC is way too simple. In justification, let's say that the DAC function is not the main one, it is more of an analog headphone amplifier. A strong feeling that the Japanese DAC is screwed on the side, just in case. Well, you never know. 6th place.

The Tento Porta DAC 1866 stands out from all others with its sound character. Apparently, this was the main goal of the developer. The sound level is high, but you do not faint from the quality or detail. We personally have not heard any “golden age of digital” here. The sound is good, a bit rough. Medium frequencies are transmitted most well and reliably. We are confident that the device will find its fans of pure R-2R converters. The headphone amplifier is very well made; judging by the complete absence of subsidence from the load, the device has a powerful buffer and zero output resistance. 5th place.

FiiO E18 Kunlun performed very strongly. You don't expect such a sound from 1798. Such a democratic affordable high-quality level. The gap from the leaders is quite small - at a very attractive price. The model is definitely successful. High frequencies are very clean and detailed. Great sound. 4th place.

The Sound Blaster E5 blew us away with midrange detail and won us over with a very wide stereo panorama. There are literally a few left to the leaders, and if your headphones or speakers are not of the Hi-End class, then you most likely will not hear any difference. The sound is near perfect. This is exactly what we wanted from a USB DAC. You can listen for a long time even on the most expensive equipment and not see any flaws. Compared to Denon, we were unable to give preference to any of these devices. Both are on the same level, with the sound of the highest category. Shares 2nd and 3rd place.

The Denon DA-10 is a great sounding DAC. Special merit at high frequencies, the nature of the sound is closer to the audiophile than to the analytical. It feels like it has its own special interpretation. For fans of the brand and stationary devices of this Japanese company - highly recommended. Shares 2nd and 3rd place.

Oppo HA-2 bypasses everyone, although not by much, but surely. We cannot say that the sound is reference, but it is as detailed as possible, and this immediately captivates. To reveal the full potential, it is better to choose the highest quality headphones and speakers, and then something new, previously unheard of, opens up in the sound. There is no color or interpretation here. The emphasis from the equipment is immediately transferred to the music, and it's great! 1st place.

Sound in speakers

Since all USB DACs have a line output, it was interesting for us to listen to the sound not only in headphones, but also in speakers. We used the highest quality active studio monitors, 3-way Adam Audio.

We did not hear anything particularly new compared to testing with headphones. All of the above is fully confirmed. The difference in some cases is simply more obvious, since all recordings are primarily designed for listening in columns. To be fair, there are separate binaural soundtracks for headphones recorded on an artificial head, but things didn’t go further than experiments. The main conclusion is that despite their small size and minijack connector, all USB DACs are suitable as stationary sound sources - while stationary DACs are not suitable as mobile devices.

However, you will have to solve the switching problem. You can still look for high-quality cords with a minijack connector, and Chinese adapters for full-size connectors can, with one awkward movement, unscrew the miniature connector of a mobile DAC along with part of the printed circuit board and disable the device. In our testing, we specifically addressed this problem and used the new highest quality cord with Neutrik gold-plated connectors and professional Canare cable (not the slightest part of which was made in China). Next, a passive attenuator was connected based on a modified factory sample with ready-made new Neutrik/Cordial XLR cords. For the mass user, the solution of all these issues presents insurmountable difficulties in finding and buying an acceptable option. To the list of these difficulties, let's add the lack of a remote control, a screen with the current mode, and the risk of sending the mobile DAC “flying” with a sharp jerk for the headphone wire. Therefore, stationary USB DACs are still preferable in their field of use, and their sound potential is higher. But with a limited budget, the question of buying a separate stationary DAC for 40-100 thousand rubles, as a rule, is not worth it at all, the matter is limited to an inexpensive receiver and media player.

Measurements in RMAA

We have assembled a special complex for studying the behavior of headphone amplifiers at a low-impedance load. Conventional tests in RMAA are not indicative, as they do not reflect the features of operation. Tests without load show just the perfect picture, and under load the distortion grows many times.

Headphone amplifiers often suffer from the following problems: frequency response subsidence at low frequencies and a sharp increase in distortion with a drop in load impedance, and sometimes overload by 16 ohms. For comparison, the usual measurements on the graphs are shown with a dash (that is, there is no load), otherwise the value of the resistor is indicated. We have chosen the most significant values: 16 ohms, 32 ohms, 64 ohms, 300 ohms.

To obtain clean spectra and break ground loops, all DACs were connected in turn to a battery-powered MXP U400-08 ultrabook. The E-MU Tracker Pre measurement card was also powered by the laptop battery. To illustrate the absence of interference and interference, test number two, "Noise Level", is included in the list of tests.

It must be admitted that the absolute figures, except for the frequency response test, depend quite strongly on the gain level and amplitude of the test signal, so that comparison can only be made when measurements are taken under approximately equal conditions.

Distortions were measured at a test signal amplitude of −3 dB and a loudness of about 90%. If only one frequency response graph is visible, then all the others have merged into one line with it. We used 24bit 44kHz to see as much of the device's own noise as possible. Our measurement interface is limited to its own noise of about 110 dBA, which allows you to check the quality of the path. For those devices that have passport parameters, our measurements showed the same or better result.

Realtek ALC282

Venture Craft GoDAP BXD

However, time does not stand still, manufacturers of digital-to-analog converter chips introduce new chips with updated characteristics and greater functionality, followed by hardware manufacturers. Following the trend, Fostex introduced the second version of its premium DAC - Fostex HP-A8mk2 based on the new AK4490 digital-to-analog conversion chip and with other interesting innovations.

The appearance of the first model has not changed. The workmanship is also at the same high level.

The very first acquaintance with Fostex HP-A8mk2 causes pleasant impressions. The case is made of faceted thick-walled aluminum in black, and the front panel is made of glass. The build quality is very high. The controls do not play and are pleasantly pressed. The soft light of the OLED screen, the absence of LEDs that burn out the eyes and excessive overloading of buttons, a strict design - everything indicates that the manufacturer cares about the consumer from the very beginning.

The volume is adjusted, as expected, in decibels in 0.5 dB steps. Moreover, the volume is adjustable both on the headphone output and on the linear one.

The Input Set control works as both a button and a knob. You can select the desired input, as well as enter the menu and configure the settings.

On the rear panel there are all kinds of switching connectors, including Analog In and Digital Out, which are extremely rare for household appliances. But first things first.

The manufacturer claims for the device support for all possible digital audio formats from 44.1 to 192 kHz with a resolution of up to 32 bits, as well as a DSD stream with a frequency of 2.8 to 11.2 MHz. For Apple computers, the DSD frequency is limited to 5.6 MHz, and for playback from an SD card, it is limited to 2.8 MHz.

The USB input works with its own driver. It has asynchronous operation, ASIO output and DSD support. (Asynchronous mode is a standard requirement for all modern DACs. It allows you to control the transfer rate on the receiver side, receive data in a buffer, and use your own high-quality oscillator next to the DAC.)

There is also a slot for an SD / SDHC card with the ability to play WAV, DSF and AIFF files from it, which not only adds functionality to the device, but also makes it work independently.

I would like to note the new remote control - with more comfortable rubber buttons and an increased number of functions.

The menu offers a rich selection of settings, of which the most interesting are those that directly affect the sound quality:

• Up Sampling, possible selection: x1, x2, x4 - multiplying the sampling rate before feeding it to the digital-to-analog converter chip
• Digital Filter, the possible choice consists of five options:
  • Short Dly Shap
  • Short Dly Slow
  • Sharp Roll Off
  • Slow Roll Off
  • Super Slow
• MSCK Sel, possible choice: Dir or XTAL - choice of synchronization method
  • Dir - synchronization of the digital-to-analog converter from the signal clock restored by the S/PDIF receiver
  • XTAL - using an internal high-quality clock to synchronize the DAC
• Direct, possible selection: On, Off - when the On mode is turned on, the volume control of the line output is inactive, the volume is always maximum

In addition to the USB-ASIO driver, the manufacturer offers a nice and minimalistic player that works via the ASIO driver exclusively with Fostex products. The sound when using it is excellent.

If you remove the top cover, you can make sure that everything is organized quite competently inside.

The headphone amplifier and post-DAC filter are designed on discrete elements, without the use of operational amplifiers. Power supply stabilizers are also discrete. Used capacitors in analog and supply circuits - audiophile Nichicon Muse and ELNA. The D/A converter chip is a new chip from AKM, AK4490, which has a signal-to-noise ratio of 123dB and a KG below -112dB. In addition, AKM has added three new sound filtering modes.

For frequencies that are multiples of 44.1 and 48 kHz, separate quartz oscillators are used, which eliminates the need to recalculate non-multiple frequencies.

The USB controller is based on a Texas Instruments TM320C55 digital processor. It has a performance of 800 MIPS and a 40-bit arithmetic processor. S/PDIF receiver and transmitter are based on AK4118 chips. In general, the input digital part of the signal processing is built similarly to the first version of the HP-A8, but has minor differences and is marked MK2.

To control the volume, the JRC Muses72320 microcircuit is used; its binding uses Muses8920 operational amplifiers to replace the previous OPA604AP. Technically, they are similar, but Muses are positioned as operational amplifiers specifically for audio applications. In addition, the Muses8920, unlike the OPA604, are dual-channel, which suggests a more significant change in circuitry than just changing the type of op-amp.

There are also changes at the line input: instead of the previous LME49710NA, one two-channel OPA1642 is installed, also positioned as an op-amp for audio applications.

The line output and in-ear amplifier have not changed. The line output has its own buffer, independent of the ear amplifier, made on discrete elements, which is a big plus, as it reduces the effect on the sound of the resistance of the signal source and the capacitances of the connecting cables.

The output power transistors of the 2SA1930/2SC5171 ear amplifier are used to build amplifiers up to 20 W, which provides a good power margin.

Passport specifications

• Inputs:
  • USB port
  • 2 optical
  • S/PDIF
  • XLR-3 AES/EBU
  • SD slot
  • RCA analog stereo
• Outputs:
  • 2 × Jack 6.3 mm for stereo headphones
  • RCA analog stereo
  • optic
  • S/PDIF
• Supported operating modes:
  • 16/24/32 bit
  • 44.1/48/88.2/96/176.4/192kHz
  • DSD 2.8/5.6/11.2 MHz
  • USB High Speed
• Headphone Output Options:
  • Maximum power: 700 mW into 32 ohms
  • Harmonic Distortion: Less than 0.002% at 1 kHz, 32 ohm load, 100 mW power
  • Permissible headphone impedance: 16-600 ohms
• Line Out Options:
  • Frequency response: 10 Hz - 80 kHz at ±3 dB
  • Harmonic Distortion: Less than 0.002% at 1kHz
  • Optimum load resistance: 10 kOhm
• Power consumption: 24 W from 220 V
• Overall dimensions: 213×78×314 mm
• Weight: 3.8 kg

Official product page:

To measure the parameters of the DAC, a measuring stand was assembled that provides galvanic isolation of the measuring card from the 220 volt network in order to eliminate ground loops and exclude network pickups outside the device being measured. A similar stand was used to measure the first version of the HP-A8C, which means that the results can be compared directly. Stand block diagram:

The Adnaco-S1A board is used as a galvanic isolation, the measuring board is a modified Asus Essence STX with a minimum measured K G \u003d 0.0002% and a noise level of −120 dB. The system is powered by a battery and linear stabilizers that generate the necessary voltages.

USB ASIO Driver Information:

Device: Fostex ASIO Driver
Features:
input channels: 0
output channels: 2
input latency: 0
output latency: 270
Min buffer size: 2048
Max buffer size: 2048
Preferred buffer size: 2048
Granularity: 0
ASIOOutputReady-supported
sample rate:
8000 Hz - not supported
11025 Hz - not supported
16000 Hz - not supported
22050 Hz - not supported
32000 Hz - not supported
44100 Hz - supported
48000 Hz - supported
88200Hz - supported
96000 Hz - supported
176400 Hz - supported
192000 Hz - supported
352800 Hz - supported
384000 Hz - not supported
input channels:
output channels:
channel: 0 (Fostex USB Audio HP-A8 Out 01) - Int32LSB
channel: 1 (Fostex USB Audio HP-A8 Out 02) - Int32LSB

Through the driver control panel, you can adjust the buffer size and view the current sample rate.

So, the summary table of measurements in RMAA at frequencies from 44.1 to 192 kHz:

Similarly to the first version, we see excellent measured parameters at all frequencies, practically limited by the characteristics of the DAC chip. This confirms the literacy of the applied technical solutions and the absence of engineering errors. In addition, the measured data turned out to be an order of magnitude better than indicated by the manufacturer.

The spectrum of non-linear distortion at a sampling rate of 192 kHz:

The only difference from the first version that attracts attention is a slight decrease in the dynamic range due to the higher noise level. If you pay attention to the spectrum, you can see that the noise level is somewhat raised in the range from 1 to 10 kHz. The nascent hump is also in the first version, but in the second it is more extended, which gives an increase in noise. How good or bad it is is difficult to judge; The fact is that single devices even in a much higher price category reach the noise level below 110 dB, this is not a determining factor for the sound quality of the device.

Headphone amplifier measurements were carried out in the same way, but the signal was taken from the output for the second pair of ears. The output power of the amplifier was 125 mW when using 32 ohm headphones as a load.

As you can see, the parameters are just as excellent, 5 times better than the declared ones, and almost do not depend on the resistance of the headphones. This confirms the high overload capacity of the ear amplifier. It is also worth paying attention to the low mutual penetration of channels under load. For amplifiers with a low-power power supply, this parameter increases to -70..-80 dB, then everything is in order.

Well, now the most interesting thing - let's consider the Digital Filter filtering modes, 5 filters with different parameters. By itself, the digital filter (DF) is an integral part of any modern DAC. Basically, its function is to shift the DAC conversion products to the high-frequency region, where they will have less effect on the useful signal and can be filtered out by simpler (and therefore less affecting the audio, audible signal) analog filters. Also, the digital filter function is the additional suppression of those frequencies in the reproduced signal, which, according to the Kotelnikov theorem, go beyond the operating limits at a given sampling frequency. In simple terms, the digital filter in the DAC chip serves to ensure the most correct reproduction of the useful signal and filtering out everything that is not such a signal.

However, everything is not so simple. The main disadvantage and the reason for the appearance of various types of digital filters in one microcircuit is the reaction of the digital filter itself to a pulse signal. Here is what AKM itself tells us about this:

The table shows the graphs of the response of the AK4490 chip to a single pulse at various settings in its digital filter. It is easy to see that in some regimes the oscillatory process outside the pulse is more pronounced than in others. This is the response of the digital filter to a pulsed aperiodic signal. There is nothing wrong with this, it is a purely mathematical transformation of a signal with an infinite spectrum that goes beyond the limits of the Kotelnikov theorem and never occurs in real musical material. Moreover, knowing the response, it is possible to inversely transform and recreate the type of filter through which the signal passed, that is, the response of the filter is directly related to its characteristics.

Let's leave the impulse response for a while and pay attention to the measurements of the frequency response of our Fostex at various settings of the digital filter:

And once again, with a linear frequency scale:

It is clearly seen that the decrease in emissions after exposure to a mythical pulse with an infinite spectrum occurs due to a decrease in the filter gain at high frequencies - roughly speaking, a decrease in its bandwidth in the high-frequency region. The frequency response of the Dly and Roll-Off filters overlapped, because spectrally they process the signal in the same way, but the response is distributed differently in the time domain. That is, for the low latency mode (Dly), the pulse edge is processed with little or no distortion, but then a longer response loop follows. In the mode with a long delay (Roll-Off), the response at the output appears even before the arrival of the pulse and also disappears symmetrically after. This happens because there is a delay line in the digital filter, the signal of which is mathematically processed and only after that it is fed to the output of the digital-to-analog converter. In the Dly mode, this delay is minimized, but this does not play any role for the listener. What difference does it make if the signal arrives at your ears 0.67ms or 0.14ms (for Dly mode) after the track starts?

Why is all this necessary? The answer may be different for everyone. The author of the article believes that marketers play an important role here, because each new feature increases attention to the product. At the same time, it is not so obvious how much the user really needs it. That is, we apply a pulse with an infinite spectrum to the input of the DAC, which mathematically cannot be correctly processed by it, and heroically fight the consequences by various digital filter settings. And the fact that high frequencies turn out to be cut off - well, excuse me, but the impulse is more or less. That's the whole point of marketing: EQ is presented to us as something completely new and a panacea. Chip design engineers and audio equipment designers are forced to follow this path, there is nothing to reproach them with.

However, there is another side: in some cases, for each particular person, certain music and equipment, this or that filter may be subjectively preferable. The AKM table attempts to shed some light on this issue. For example, if you do not like harsh sound, you can set the Super Slow digital filter mode with a smooth treble decay, and nothing will annoy you, the instruments will be approximate and more natural. Dly's low latency modes should theoretically sound better for drums and driving music. But if the maximum quality of reproduction of all frequencies is important to you, then the standard Sharp Roll-Off mode will have no alternative.

If you're worried about impulse response - no self-respecting record label will ever allow a track to be released with frequencies that are outside the theoretically acceptable range, and therefore, all these response pictures make almost no sense in real music. In simple words: if you limit the spectrum of the test pulse to the notorious 22.05 kHz, then all the graphs will look almost the same, there will just be a slightly different slope of the pulse shelf, which is reflected in the frequency response measurements. Since the frequency range of music is limited in the same way, the different frequency response decay of the digital filter will be much more affecting the sound than its impulse response outside the operating frequency range.

It is also interesting to compare the performance of AK4399 in Fostex HP-A8C and AK4490 in HP-A8mk2 in Sharp mode at different sample rates:

44.1 kHz

96 kHz

192 kHz

In the 44.1 kHz mode, both microcircuits show almost the same result, however, with an increase in the sampling frequency, the AK4399 has a noticeable decline at low frequencies, and the AK4490 - at high frequencies. And if the HF rolloff in the AK4490 is most likely programmed to improve the impulse response (frequency response above 20 kHz is no longer so important), then the LF rolloff in the AK4399 is most likely some kind of flaw in the chip or its digital filter. In any case, I would prefer to listen to highres on the AK4490, which, in general, was confirmed during the listening.

A few words about the use of Up Sampling and Digital Out. Upsampling performs two functions. The first one adds "missing" readings. Due to its internal algorithm, it tries to do this as accurately as possible, “thinks out” what was lost in the original signal with a low sampling rate. The second, secondary, function - the upsampler acts as an additional filter, shifting noise and DAC conversion products to a higher frequency, inaudible region. As a rule, all this leads to an improvement in the intelligibility of the sound, the micronuances of the recording, echo, room volume, etc. are better transmitted, but only if the DAC itself digests high sampling rates well.

It would seem, why does the DAC need a digital output? And then, that the same thing is fed to it that is fed to the internal DAC chip! That is, you can send a signal to the S / PDIF or USB input of the Fostex HP-A8mk2, improve the clock using the XTAL setting, increase its frequency by 2 or 4 times (or leave it unchanged) and then apply it to another DAC - for example , a class above, but without USB. In addition, the S / PDIF-out has sound played from the SD card, that is, this DAC can also be used as a transport. All this expands the possibilities of using the device.

Listening

When listening, headphones from various well-known manufacturers were used. Since the headphone amplifier has not changed in the model, the results of listening to music with headphones on the HP-A8mk2 are almost the same as those of the previous model HP-A8C.

The volume level provided by the built-in amplifier is more than enough to drive the tightest headphones. No obvious dips in dynamics and distortion were noticed when using low-impedance headphones. The volume control is neat, there is no strong dependence of the timbre on the position of the volume control. And only at very quiet levels there is a noticeable decrease in the detail of high frequencies.

In general, the sound quality of the Fostex HP-A8mk2 is high and more than good for its price, both when outputting sound to headphones and at the line output. There is no distortion of timbres, the sound is "live" and open. The positioning of the instruments (stage) is available, and in terms of its scale it corresponds to what much more expensive devices give out. The subjective perception of sound in this device does not cause negative feelings or desire to listen only to a specific style of music.

Replacing the AK4399 with the AK4490 had a positive effect on the sound: the sound became more accurate and soft, the transmission of the timbres of the instruments and especially the voice improved, although in general the presentation remained the same, which cannot but rejoice. Bass has improved significantly - it has become more embossed. The sound of the line output in terms of timbre color and perception does not differ from the headphone one.

Enabling the Direct option disables the volume control on the line output. In this case, the improvement in sound quality is more pronounced than in the previous model. There are more small details, echo, the sound becomes freer. Whether this is due to the installation of a new DAC or a change in the volume control circuit, it is difficult to say, it is necessary to listen to both devices, but we did not have such an opportunity.

Using Up Sampling does not provide clear advantages. With it, the sound becomes softer and more accurate, but at the same time, the high frequencies are muddier and part of the dynamics in the sound is lost. It may be necessary for certain music (classical, for example), it is worth checking personal preferences. It is worth noting that the AK4490 "digests" higher sampling rates better, the negative aspects when using Up Sampling are much less pronounced than in the previous model.

The settings and effects on the sound of the Digital Filter have already been described in sufficient detail. The choice of a particular filter and sound color is a matter of personal preference.

MSCK Sel, we would recommend always setting it to XTAL - it's much better, especially if the source of the figure is not of very high quality. When using a high-quality digital source, the subjective difference between the modes decreases, but does not disappear completely.

Taking into account all of the above, we conclude that the new Fostex HP-A8mk2 is a reasonable evolution of an initially successful product. The cost of the device is 84 thousand rubles, it is a worthy competitor to products in the same price category. The ability to use as a DAC, upsampler and headphone amplifier make the Fostex HP-A8mk2 a three-in-one device. The modern DAC, support for all audio formats and the natural sound of the new Fostex USB DAC deserve close attention of music lovers.

USB as a universal way to connect devices of various purposes has become so firmly established in modern life that one should have expected the appearance of Hi-Fi components with such an interface. And this actually happened. We recently tested digital converters that allow you to use a computer as a music source, and now we have assembled amplifiers with similar capabilities. They are still few, but you can already see a clear perspective for the future.

IN FACT Implementing a separate path with USB into a Hi-Fi component is easy and quite inexpensive. A bus controller chip is installed, and the signal from an external source (computer) is then redirected to the built-in DAC and then fed through the input switch to the audio path. However, such a scheme looks logical only for those devices that already have such a DAC. That's why CD players and multi-channel receivers were the first to get USB jacks, then external converters. But now more and more stereo amplifiers have begun to appear, which have USB on the rear panel. Why does an analog, in fact, device need a socket for a computer cord?

Here it is worth immediately dotting the "i". Some electronics manufacturers in this way only leave the user the possibility of software upgrade of control, indication or processor sound processing algorithms, if such modules are in the component. For obvious reasons, we did not include amplifiers in which the USB socket is not intended for transmitting a musical signal at all.

In other developments, too, not everything is so simple. Due to this, some companies only expand the functionality of their integrated or preamplifiers - USB is a nice, convenient, but far from the most important bonus here. Say, now you can connect a PC, but the sound quality is not regulated. However, there are already such components in which the USB bus is allocated as the main one or acts on a par with traditional analog inputs. And theoretically, it can really compete with any other transmission methods, because the USB protocol itself is so arranged - it allows the so-called asynchronous mode. The data in it is transmitted not in the form of a continuous stream that is not protected from jitter, but with a block integrity check, with a reverse channel for error correction, and only then, when the proper array accumulates at the receiving end, is it sent for bit-to-bit conversion, as in original code.

It was on an in-depth study of the quality of transmission over the USB protocol that the entire test methodology was built in this review. We will not describe the functionality and internal structure of each amplifier, but will focus on the sound of amplifiers in all modes and will look for even the slightest differences when switching from analog to digital input. And in order to minimize subjective errors, we have also brought musical programs to a “same denominator”. Everything that was played on the reference CD player was pre-stored on the computer as exact WAV copies and played by the standard iTunes software player in linear mode with sound and spatial effects turned off.

DEVICE FOUND

"Good buy" integrated amplifier looks from all points of view Pioneer A-A9MK2. And the price is attractive, and the sound quality (whatever input you choose) will not leave you indifferent. This device has a really cool DAC and a proper USB controller on board, which receives data from the computer without any degradation. It is even a little pity that this functionality is not extended by other digital inputs.

But all this is in another Japanese product - preliminary Onkyo P-3000R. It is strict and solid, made with impeccable quality, has no equal in terms of versatility, because you can connect not only a computer to it, but everything in general - from a vinyl turntable to a studio recorder. For this, and for the soulful, detailed and very clear sound that it delivers when paired with a two-channel driver Onkyo P-5000R, he gets "Expert's Choice".

No matter how much the “digital” NuForce ICON 2 surprised us with its sound perfection (especially when using analog inputs), we do not recommend considering it as a full-fledged high-fi component. And the point here is not at all in its class, glamorous appearance or limited functionality. When working via USB, it simply will not be able to produce the proper sound pressure with some "adult" speakers. Although for desktop audio, ICON 2 will probably be the most competent and interesting acquisition.

The summary for the Musical Fidelity M6i will be drawn up on diametrically opposed formulations. First of all, this is a very outstanding audiophile-level integrated amplifier. But USB is clearly added here on the principle of "so that it is." By analogy, the M6i produces such a svelte, strong, polished sound that switching to listening to music from a computer can be a little disappointing.

measure 7 times

The frequency response of the amplifiers was taken in the range of 20 Hz - 20 kHz at the extreme positions of the tone controls, if any. We also revealed the dependence of THD on the output power at a load resistance of 4 and 8 ohms, they are shown in the graph in red and green, respectively. From these curves, one can judge the power-to-weight ratio of the power source and, as a result, the dynamic characteristics of the amplifier. The spectrum of harmonics, as always, was filmed at a power of 1/10 of the maximum (power at 1% distortion was taken as it). We were unable to characterize the NuForce Icon 2 amplifier, as there is a signal delay in its digital path, which the Clio measurement system perceives as a huge signal phase shift.