Critic's Corner

Posted by ataffel_tas (R) on July 5, 2009 at 16:48:26

In Reply to: RE: Did I miss the discussion re: the latest TAS article on USB DACs ... posted by Stephæn on July 1, 2009 at 08:28:06

I am delighted to see so much interest in my recent TAS article on “The State of USB Audio”, even though much of what has been written here and elsewhere takes issue with my methodology and findings, not to mention questioning my competence! Because this is such an important and timely topic, I thought it appropriate to clarify and expand upon elements of my piece, and to respond to accusations that have been leveled against me personally.

The article’s perspective: I believe it is important to understand the purpose and intended readership of the article. I consciously approached the topic of USB audio from the perspective of a typical high end audiophile (that is, a typical TAS reader), who is not necessarily a computer whiz. My aim was to determine, from this perspective, the results that could be achieved from USB both on an absolute and relative basis. My goal was not to assess USB in a vacuum, nor was it to determine what a highly sophisticated user might be able to do with it. In general, high end audio does not require those who enjoy its products to have expertise in those products’ inner workings. For computer audio to be broadly relevant to this market, it must meet this criteria as well as sounding good.

The author’s qualifications: Although many posts have implied otherwise, I am actually quite proficient in computer technology. I hold a degree with honors in Information and Computer Sciences, and have had a twenty-year career centered around data communications protocols. Suggestions that I might not understand the technicalities of asynchronous USB, for example, are incorrect. However, as noted above, my purpose was not to approach this research from the perspective of a computer expert.

Bias against USB: Quite a few posts have alleged that I was pre-disposed against USB, presumably because my results were less than glowing. By this logic, any negative review of any component or technology could be chalked up to bias rather than impartial observation. However, the fact is that I would have absolutely no reason to harbor such a bias, and indeed I did not. On the contrary, I would have enthusiastically reported more positive results, and I was disappointed at the actual outcome. I think the fact that I employed three different PC’s (from different manufacturers and running different operating systems), tried vainly to include a Wavelength example, tested multiple DACs and software programs, and even experimented with expensive USB cables attest to my efforts to give USB every opportunity to shine. Whether or not you agree with my results, know that they were based solely on what I heard. At the same time, it is worth noting that many of those suggesting, without foundation, that I have a bias actually do have a demonstrable, commercial motivation for promoting USB and for denigrating any negative opinions (and their source) about the interface.

The choice of DACs: For this project, I tried to round up as many exemplary USB DACs as possible. Audio Research and Bryston were chosen because both firms have solid engineering and build quality, and both understand good sound. Benchmark employs a highly respected, purpose-built USB input module. I sought mightily to include a unit from Wavelength because, as noted in the article, its technology is innovative and I actually do understand its promise. Wavelength refused to participate (more on that below) and Ayre, which uses similar technology, has by its own admission completely severed ties with TAS. Ergo, these latter two units were not available to me. Their lack of inclusion is unfortunate, but cannot be construed, as some have, as a desire on my part not to give USB its due. The units were excluded by their manufacturers, not by me.

Wavelength’s withdrawal: I have not been at all surprised to read Gordon Rankin’s reaction to my article, or his statements about my qualifications to review his equipment. In response, I would simply say that if I, with my education and experience, am not qualified to get the best out of his gear, then neither is TAS’ readership. However, I believe the issue of my qualification is a red herring. In our conversations, Gordon became familiar with my background and—although he now states otherwise—indicated comfort with it. As evidence of this, note that it was after these conversations that Gordon sent me a Cosecant for review. Things fell apart over a different issue: my intended test bed. Gordon’s preferences in this area are well known: powerful Macs with SSDs and massive amounts of RAM running iTunes. I did not feel such a configuration would be typical of our readership, and when I indicated the test beds I planned to use, along with my (valid) issues about iTunes, he demanded the return of his unit. As much as I would have liked to have heard the Cosecant, my feeling is that if Gordon’s recommended configuration is a prerequisite to his DAC (and by extension, USB itself) sounding good, it only reinforces my conclusion that the interface is not yet ready for the world of high end audio. Still, I wish Gordon had had the courage to subject his DAC to a controlled evaluation—where it would be compared to other USB and non-USB DACs—in a typical audiophile environment. I am certain the results would have added significantly to the conversation.

USB vs S/PDIF: Some posts have argued that USB actually does sound better than S/PDIF, if only the right DAC is used. These posts point to good experiences with DACs from Wavelength and Ayre, and the positive review by my colleague Steven Stone of the Streamers products. The fact that USB can sound pretty good (or even very good under narrow conditions) does not mean it is better than S/PDIF. I think it is noteworthy that none of the aforementioned products offers an S/PDIF input, making a true apples-to-apples comparison impossible. On the other hand, I used DACs that did enable such a comparison and in every case, including the Benchmark—which certainly does not treat USB as an “afterthought”—S/PDIF sounded clearly superior. Please don’t take my word for it, try it yourself—if you can be unbiased.

USB vs FireWire: I am glad to see that no one (yet!) has challenged my assertion that FireWire is a superior means of getting audio out of a PC. Several posts have actually pointed to technical reasons why this is true, and I would simply add that FireWire excels without the need for the elaborate technology patches USB apparently requires. My statement that “no FireWire DACs exist” was meant to say “no audiophile grade FireWire DACs exist”, and I owe readers an apology for not being clearer on this point. As many posters have rightly pointed out, there are a number of pro FireWire DACs available. My intent was to challenge high end companies to make a similar product built specifically with high end consumer sensibilities in mind. Perhaps this is one area in which we can all agree.

I hope the above serves to clarify what I was trying to accomplish with my report, and puts my results in a clearer context. Within that context, I believe those results are completely valid, and will prove useful to their intended audience. And while I don’t have the time or resources to engage in one-on-one discussions with everyone commenting on the article, I do look forward to reading additional comments.