I can't believe I'm getting drawn into this discussion, but anyway....
The quoted statement is true, provided that all the 0's sent by the source are interpretted by the receiver as 0's and all the 1's as 1's. Then we have perfect digital transfer, and indeed it doesn't matter where in the chain we interpret it - it's always the same. Life would be sooo good if that was all that there's to it :)
Unfortunately, there's no such thing as digital data transfer - the signal is only interpretted as digital, based on some protocols or conventions that both sender and receiver understand. The irony is that the physical connection between the two devices is analog. Based on the convention, the receiver detects increases and drops of the voltage on the line at specific time intervals, and quailfies them as 1's or 0's.
Once we understand that, it's not too hard to imagine how certain interferences can create problems with this transfer - anyone who ever listened to a short wave radio knows what I'm talking about.
The digital world is pretty clever though - the voltage differences between 1 and 0 signals are large enough to ignore the impact of most garbage that would totally destroy any analog transmission; there are checksums that allow detecting transmission errors; there are redundant protocols that transfer the data correctly even with certain percentage of errors; there is handshaking which allows to re-send the corrupt data packages. In other words: it should be flawless.
The only aspect that could shake this nearly perfect world is timing: if the data cannot reach the destination in time to be processed, we're going to hear it.
Having said all that, I can imagine some situations in which a quality USB cable may help:
- in the engine room of a nuclear powerplant
- within 200m radius of a TV transmitter (OK - I'll allow mobile transmitter stations as well)
- under a high voltage powerline
In all other situations, if you hear difefrences in the warmth of the tone or tighter bass with one USB cable but not another, it's only because God makes it so.