A: No. As might be expected, there are significant variations in the quality of USB sound from different DACs. Among the four I evaluated, the Bryston and Resolution Audio have relatively poor USB sound. Meanwhile, the extra effort exerted by Benchmark and Audio Research has paid off in far richer timbres, more neutral tonality, and greater extension. The Benchmark and ARC don’t entirely circumvent USB’s flaws, but they do a good job of minimizing them.
Q: How does a USB-to-S/PDIF converter compare to straight-through USB?
A: Based on my experience with the Bel Canto USB Link 24/96, a converter can sound as good as or better than straight-through USB. (To read my review of the Bel Canto USB Link 24/96, click here).
Q: Do USB cables make a difference?
A: Emphatically yes. Much as I would love to report that USB is one area where wires are a non-factor, the interface proved no different in this respect than any other. Cables do make a difference, and a rather significant one at that.
I tested four USB cables: a stock “Brand X” strand that came with some peripheral I own (probably a printer), a Belkin Gold Series model ($44.99), a KimberKable ($50), and the dearly-priced Synergistics Tricon USB ($550). Of these, the generic and Kimber Kable cables were the least satisfactory—both reinforced USB’s synthetic quality. The Synergistics Tricon thankfully did not suffer that shortcoming, and was laudable in most every other way. However, the cable was notably bright. This trait can actually be an advantage in some applications. For example, if I owned a Bryston BDA-1 and were using its USB input, I would not be without the Tricon. Its top-end boost does indeed synergistically counteract the Bryston USB input’s high-frequency deficit, allowing instruments to breathe and strings to sound more like themselves. However, with more neutral associated equipment, such as the ARC DAC7 or the Bel Canto USB Link 24/96, the Tricon’s brightness exacerbated the shrieky nature of USB strings.
The best overall USB cable I tried was unquestionably the Belkin Gold Series. A huge step up from generic cable, the Belkin was very nearly the equal of the Tricon in every particular, with the added benefit of being dead neutral. The fact that it can be had for less than fifty bucks is a great bonus. For now, the Belkin Gold is my reference USB cable.
Q: Do Macs sound better than PCs (or vice versa)?
A: Not in my experience. In the course of my testing I did not detect any particular advantage of one OS or computer manufacturer over another. My iMac running OSX sounded very much the same as my HP running Vista when I compared them back-to-back playing the same music. Any minor differences paled beside the predominance of the “USB sound,” which was unwavering between machines.
Q: Does music software make a sonic difference?
A: A definitive answer to this question will have to await a more exhaustive—and no doubt exhausting!—survey of the myriad popular options. These include iTunes, Foobar, MediaMonkey, Windows Media Player, Rhapsody, RealPlayer, and many others. However, to get a taste for the subject, I did listen closely to Foobar 2000 and MediaMonkey playing the same music from the same HP laptop. I found that Foobar sounds a bit more open than MediaMonkey, probably due to its Kernel Streaming feature (not to be confused with XP’s kernel mixer), which bypasses more of the operating system than MediaMonkey can. But the difference was very slight, and insufficient to woo me away from MediaMonkey’s friendlier user interface.