Why do digital cables sound different?

I wasn't trying to start a religous war here when I asked the question. I'm just confused. With analogue, it makes sense that if there is an impedence mismatch (among other things) that these factors can change the signal being transmitted. The problem is that with digital and such a short distance to move the bits, unless you have a bad cable (where you get a lot of errors), shouldn't ALL good cables move them the same way and thus represent sound the same way? With all the techie types out there involved in audio, I was thinking that someone would have already taken measurements at the sending and receiving side to see IF the digital stream is the same. Isn't it ONLY if the sreams are different, at the two ends, with various cables that there will be a difference in sound? This is fairly basic, no? There is no magic involved...and if the digital stream at the receiving end is different than at the sending end regardless of how it sounds...it is just wrong! Or am I missing something here and not understanding what's involved??? What I am interested in are the possible reasons that cables COULD sound different. My only guess so far is that a weak signal or interference makes it hard for the receiving end to distinguish what is a 0 and what is a 1... I think this was inferred by Sugarbrie It is also my understanding that the Pros use a different digital signal...and that the voltages are higher (and making the difference between a 0 and 1 more easily discernible?). Can anyone hear differences in using different cables on aes/ebu? Thanks!

WOW, this is a MUCH better response than I'd anticipated when I asked the first question. Thanks to everyone for the feedback. The wide spectrum of expertise in this forum is astounding! Now to stir the pot a little... Through this discussion, we have some idea of what may be going on within the cable and the interaction of the cable and sending/receiving mechanisms. However, what is the difference in the sound that is perceived? This is my thinking...If the stream is just 1's and 0's...what happens when there is degradation? How does it manifests itself? There seems to be a few phenomena that could occur...scrambled bits, missing bits, signal too low (too hight), timing errors, etc. To me, errors in the data stream would sound like dropouts/static, even wrong notes, etc. and not the same type of subtle differences as in analogue cable. However, there are reports of more bass, the highs being too bright, etc. There are even reports of digital cables with the "family" sound of the company's analogue cables. How can this be possible? As well, if not bits are lost, what difference does timing errors make? Isn't part of the reconstitution of sound at the receiving end, reclocking the signal? Sorry for so many questions, however this thread has been very interesting and educational! Thanks everyone!