People are always asking whether USB or S/PDIF is better. To me the only "better" I am concerned with is better sound. I really don't care that much about which one measures better on a test bench. If specific measurements equate to audible differences then I'm all ears. One very popular topic related to this discussion is Jitter. Jitter is commonly referred to as the antithesis of good sound. Toslink is often considered the worst connection because of very high jitter measurements. Does that mean USB is the better method of getting digital music to your DAC? The S/PDIF fans suggest that USB is inferior and not ready for prime time. Since this is an election year in the US, I decided to find out for myself whether I'll be voting for USB or S/PDIF.
It's been very crazy around here lately. Having just moved across town this week 99% my gear is still boxed up. It's kind of hard to review equipment while it's in a box unless you're from Maxim Magazine. If you hadn't heard, Maxim published a review of the new Black Crows album without even hearing once! So, I've been using my iPod Touch for keeping up with the forums and answering emails.
Anyway, the whole USB v. S/PDIF question is one I've been working on quite a bit lately. I've talked to people who know digital audio conversion so well that it's scary and I've done my own listening tests. Based on this my conclusion is, people that boldly answer "USB is better" or "S/PDIF is superior" are 100% incorrect. Neither one sounds better than the other in all systems, in every room, with all music etc..
The most common thing I hear from industry sources is that properly implemented USB is in theory superior to S/PDIF. The measurements are often better when it comes to jitter, but no doubt there are some tests that prove the opposite. In fact some manufacturers with nothing to gain by the success or failure of USB would prefer to have only USB inputs on their DACs. It is probably safe to say that the components manufactured by these folks perform best via USB.
On the other hand most of the arguments against USB have more to do with computer operating systems and a general lack of understanding from the audiophile community. A very common knock against USB has to do with audio drop-outs. Even I was plagued by audio drop-outs while listening through a USB DAC. Since I am sold on USB as a major player in high performance audio I knew the problem had nothing to do with USB itself and everything to do with my particular setup. I often read posts on other forums that decry USB DACs based on some Windows Vista issues totally unrelated to the DAC. These snowballing posts usually don't add any clarity to the situation. It is also a fact that some USB inputs, and others, are just converted to S/PDIF inside the DAC. This certainly isn't a deciding factor one way or the other, just a bit of information to consider when researching your next purchase.
While I don't like to use other reviews in support of a point I am trying to make, I will bring up a general theme others have written about. The reviews of DACs with both USB and S/PDIF have gone both ways. Two very popular high end DACs in recent print magazine reviews have had the reviewer praising the S/PDIF connection over the USB connection. After reading these reviews it would be easy to conclude that USB is just not ready for the big leagues yet. However, the USB implementation on these specific DACs may have been an afterthought or done without as much R&D as the S/PDIF inputs. There are so many variables involved in this issue that one will perhaps never be able to give a solid black & white answer to the question of USB v. S/PDIF.
As I always do I relied on my ears to make a decision for me. The answer I arrived at probably won't make you as happy as the recent "Bluray Wins!" announcements. I listened to music that I am intimately familiar with via USB and Toslink. Some pristine recordings and others that will never be mentioned in audiophile circles (unfortunately). Note: If I could only pick one album in the world to be remastered it would be the Red Hot Chili Peppers' Californication. Awesome music, but no doubt one of the word sounding overly compressed albums of all time. After hours of listening my conclusion was that there is no winner. (How lame is that you must be saying). I noticed small differences that didn't necessarily equate to good or bad differences. I often thought I had heard something only via Toslink or vice-versa. Then I would switch back to USB and hear the same thing. In the system I used for this article the differences were so small that I could live with either USB or Toslink and be totally satisfied. I would lose nothing by getting rid of one of the inputs. Remember that this is only for the specific system I used for these listening sessions. I have no doubt that other systems will perform unequally with USB and S/PDIF. Again, much of it depends on the implementation of USB in the DAC. So, barrow a DAC for the weekend from your local dealer and spend some serious time with it. Maybe USB will sound better. Maybe it wont. At least you'll spend hours listening to good music.
System used for this article:
MacBook Pro laptop
Benchmark DAC1 PRE
Kimber USB Cable
Monster LightSpeed 100 Toslink to Mini-Toslink
Note: If you find a better Tos to Mini-Tos cable please let me know. They are very hard to find without using an adapter.
Sennheiser HD600 Headphones