Seems I'm a bit late the the usb cable party Since I don't want to add any more fuel to the fire and I stated my opinions in my previous post, I only want to say something about two points that are really bugging me:
That has been said not only about digital cables, but also about analog cables. Each of my analogue cables (RCA and 3.5mm connections) has its own sound profile. Some of them when compared side by side, sound quite similar and I could take someone telling me that there are no differences in SQ between them. But, others just sound different enough that I would have to lie to myself if I said that it is possible that they sound the same, just to keep someone else happy. I just tested two digital cables and found out that there are differences in SQ, just like they happen with analogue cables.
Analog != Digital. Yes, Digital still uses analog means to transmit it's data but through the stuff put on top of that, the digital world is not comparable to the analog one. It has a very distinct set of rules, so that you can not apply your knowledge/experiences from one side to the other.
We would not have USB cables without technicians, like macbug. I respect that. We would not have better USB cables without good observers. I respect that, too. So, instead of getting mad with the "because of the ones and zeros all sound the same" argument, I am looking forward to find a technician that would acknowledge what the observers are hearing. My printer cable and my solidly built DAC cable do not sound the same. I just observed that and I will not be mad at anybody for not believing me. I am past at getting mad for stuff like that. Way past.
Will never happen. Bring this discussion to any technician/engineer who works with this stuff and he will tell you the same things. I discussed it with a colleague of mine, who is our hardware design guy, and he came to the same conclusions as macbug or me: As long as the cable conforms to the USB specifications and is properly shielded (which any USB 2.0 cable should be, since the standard specifies it) there is no technical approach where it could modify the sound.