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This review first appeared in the April 2012 issue of hi-end hifi magazine High Fidelity of Poland. You can also read it in its original Polish version here. We publish its English translation in a mutual syndication arrangement with publisher Wojciech Pacula. As is customary for our own articles, the writer's signature at review's end shows an e-mail address should you have questions or wish to send feedback. All images contained in this review are the property of High Fidelity or M2Tech. - Ed

Reviewer: Wojciech Pacula
CD player: Ancient Audio Lektor Air V-edition
Phono preamplifier: RCM Audio Sensor Prelude IC
Cartridges: Miyajima Laboratory Shilabe, Miyajima Laboratory Kansui
Preamplifier: Ayon Audio Polaris III Signature Version with Regenerator power
Power amplifier: Soulution 710
Integrated amplifier/headphone amplifier: Leben CS300 XS Custom Version
Loudspeakers: Harbeth M40.1 Domestic
Headphones: Sennheiser HD800, AKG K701, Ultrasone PROLine 2500, Beyerdynamic DT-990 Pro 600Ω version
Interconnects: CD-preamp: Acrolink Mexcel 7N-DA6300, preamp-power amp Acrolink 8N-A2080III Evo
Speaker cable: Tara Labs Omega Onyx
Power cables (on all equipment): Acrolink Mexcel 7N-PC9300
Power strip: Acoustic Revive RTP-4eu Ultimate
Stand: Base under all components
Resonance control: Finite Elemente Ceraball under the CD player, Acoustic Revive RAF-48 platform under the CD player and preamplifier. Pro Audio Bono platform under Leben CS300
Review component retail in Poland: zł1550, zł1650, zł1550

This review is primarily focused on the hiFace EVO DDC which converts USB computer signal into any of the five types of signals ‘understandable’ to a classic D/A converter: RCA, BNC, TosLink, I²S, AES/EBU ST. Its operation can be further improved by applying the EVO Supply, an external battery PSU and, through the BNC input, adding the EVO Clock, an external precision master clock. I also tested those two devices.

Auditions, tests, reviews, meetings about computer-related products, audio files especially in high-resolution… all this still resembles walking through a minefield. It would seem that we have mastered a few basic skills already, understand a bit more and learn quickly. It is common knowledge that one of the worst enemies of digital audio signal is jitter, i.e. lack of clocking precision. Less common is awareness of various types of jitter - correlated and uncorrelated, short- and long-term and their various combinations. But for arguments’ sake let’s assume that the awareness of this is quite satisfactory.

When it comes to computers we are usually helpless as babies regardless. Here it is the insights of computer geeks, software engineers, IT specialists and other trustworthy respected people (I say this with absolute conviction) which are most important and significant. What they say is that in the computer realm the vast majority of our concerns about digital audio systems are not applicable. It is difficult to discuss this with them at the meta level because according to theory commonly accepted both in academic circles (pure theory) and engineering (applied theory), the computer is an ideal sound source and USB is the best possible interface. Computing capabilities seem almost endless at least in the context of the CD player and USB transmission bandwidth ‘precludes’ any problems. This, they say, is the ‘pure’ sound source, the perfect source.

Except in this case theory does not meet practice, at least not in the perfectionist terms we deal with in the high-end audio industry. As a result of our sensory experiments we—audiophiles, thinking and practicing scientists, engineers and end users—have managed to identify areas where there seems to be dire need to verify the computer world’s operating theory. I'm not saying that it needs to be overthrown. Absolutely not! I mean something that is normal in every field of science, namely innovation and shifts in understanding that do not change basic assumptions yet significantly affect the end results.

What we already know is that the computer is one of the most difficult-to-master digital sources. Its computing power is actually the least important component. What gains importance are the methods of internal signal transmission, its treatment, management and the power supplies. The problems are many. This could be plainly seen with the software player JPLAY. The program beats popularity records in audio circles, wins multiple awards, is warmly discussed by the biggest audio magazine etc. How did it happen that two enthusiasts—Marcin Ostapowicz and Josef Piri—came up with something that easily beat products from recognized software companies who had already developed this type of software player for many years? The answer is very simple. They questioned everything that appeared to be certain and addressed the sources of all problems they identified one by one. At first these problems often seemed illogical and nonsensical. And yet their elimination changed the sound for the better. It was an exercise in applied imagination power.

The computer is one thing of course. The other is what happens once the signal departs the computer. Now it’s a different game. Here the computer guys have less to say and it’s the audio engineers who take over. As usual however, most of them are mistaken, resting on theoretical knowledge and concomitant beliefs. I am almost sure that none of those who criticize the solutions we have adopted in the audio world—repeatedly re-examined, discarded, confirmed and challenged again—carried out any such tests themselves. That makes such critics either misinformed or worse, ignorant. Argh. As has long been known, USB is a very primitive way of audio transmission and one that is very difficult to master. USB cables can dramatically change the sound. The way a DAC receives the USB signal (adaptive or asynchronous) can impact the results. And, finally, USB devices abide by exactly the same rules as other digital audio device. They aren’t immune to jitter or power supply quality.

So we come to the subject of this review. For several years the Italian company M2Tech has been offering their own solutions dedicated to both USB-S/PDIF conversion (the popular hiFace) and its decoding into the analog domain. This time we have a look at their hiFace EVO D/D converter and certain add-ons that improve its sound.