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.

Actually, if a digital waveform is distorted to the human eye on a scope, then it is distorted. There are built in test parameters you can put in to determine if the waveform is in spec or out of spec over a period of time.

Check out this link:
http://www.scientificarts.com/logo/logos.html

You don't need to know the math to see what they are talking about. There are some eye diagrams there which are very "open" and hence have excellent data transmission with no errors and there are some which are "closed" which are filled with errors.

Just 'cause its digital doesn't mean it isn't lossy.