Originally Posted by noahbickart
With modern DAC designs the cable type makes no difference whatsoever.
It is a digital signal. It either works, in which case you hear music; or it doesn't- in which case you hear static.
Use whatever you have- they'll all sound the same.
Not sure I'd agree... on a transparent system you will be able to hear differences in a lot of cases. On the same DAC a well implemented asynch USB input should be better than a well implemented SPDIF interface. Its that "well implemented" that is the important part. There are a lot of poorly implemented asych USB inputs out there that loose a lot of the benefits of "asyncness". (ie; crappy clock) There used to be a large number of dacs that just added a cheap USB to SPDIF converter in front of their existing SPDIF input, these will almost always sound worse than direct SPDIF input.
The issue is that essentially all SPDIF inputs have some mechanism to track the data rate of the incoming data. Such a tracking system can always be bettered by a fixed frequency system. That's what async does, it uses a fixed frequency local clock, and tells the source to change the overall data rate so it matches the local clock. If that fixed clock is done very well this should be better than any form of tracking.
Even today there are a large number of adaptive (ie non-async) USB inputs around, unless very well done these will usually be worse than a very well done SPDIF interface.