Why do digital cables sound different?

This is a very interesting post. Everyone who posted a comment is right; well, maybe except the one about Nicole Kiddmann.

Ideally, it shouldn't make a difference in which digital cables you use, but really, just because it is one and zeros, it is still an analog signal. It has a slew rate, overshoot, undershoot, and ringing. Any mismatch in cable impedance, terminations, or source impedances can cause some anaomolies in the digital word. When it gets bad enough, the 1's become zeros and the 0's can become ones. The same is true for optical links, too.

I wish I could post a picture here, I have some eye diagrams of high speed digital signals in the 2.5 GHz and 5.0 GHz range which are very enlightening. When the cable is lossy enough, there is very little difference in a one or a zero.

Do note that it is datastream dependent; that is, a long series of ones won't degrade like several ones followed by one zero, etc.

Why does a Big Mac taste different from a Whopper?

A digital waveform can be very badly distorted, as viewed by the eye, but a well designed line receiver will still properly distinguish ones from zeros. Furthermore, if an error is made, or even a group of errors, perhaps due to some unrelated power glitch or scratch on the CD, a data stream with error correction encoding (like a CD) will still be recovered exactly. Them is the facts.

Precisely. Which is why it is so curious that digital cables do seem to sound different from one another.

Drubin...So let's turn this question over to the psychologists. Electrical engineering has no explanation.