Why do digital cables sound different?

There is a reason. The digital signal is transferred at a much higher frequency than the audio signals. At these higher frequencies, the output impedance of the transport, the characteristic impedance of the cable, and the input impedance of the DAC must be matched in order to get all of the energy sent by the transport to be absorbed by the DAC. Any mismatch in impedance will result in some energy being reflected back to the transport. This results in standing waves which distort the signal, that is, it is different than what would ideally arrive at the DAC if all was matched. Some of the enrgy is disipated in the output stage of the transport, and some in the cable. There are other cable losses such as dieletric loss and radiation loss that are minimized by a well designed cable. This area of electronic theory is called transmission line theory and will be covered in any book on basic electronic communication theory. This is an ovesimplified explanation, but my point is that this an extremely complex subject that can't be explained by statements like, " I don't see how a wire can make any difference." I taught this subject for 9 years and the more I learned the more I realized how little I knew.

Bravo Bruce, precisely my point.

Danielho - to answer your latest post, no, there is nothing going on beyond what you're supposing - the transport generates a digital stream of data and the receiver receives it. From a technical point of view, it's either received the same as it was sent or it's not, and the benefit of a premium cable would have to be dependent on it's ability to allow the receiver of the data to get it "the same" more often than a lesser cable does. The objectivists point of view would suggest that the only way for the music to sound different would be for the bits to be different (or absent).

One of the severe limitations of the current transport / DAC technology is that there is no redundancy or error correction built into the transfer - the transport sends the data and "hopes" it gets there. If it doesn't, there is no way to fill in the hole or to recognize that it has been changed. Digital audio in the future most assuredly will be transported with a scheme that has complete error correction and redundancy which again, technically speaking, should basically eliminate any instance where the receiver gets something different than what was sent.

Then you have to decide whether the way digital data gets transported, assuming it doesn't get changed at all, can have an effect on the way the music ultimately sounds. I'm certainly not saying that people who say they hear a difference don't, but I can't explain why it would be and I haven't seen a lot of explanations. Perhaps there is something going on that is not yet explainable.

Finally, I agree that somebody in the world has to have run a test where they "capture" the data received by the DAC and compare it to the data sent by the transport, but I have never seen anyone document such a test. With all the communications advances of the past few years, I doubt very seriously that recent transmit and receive circuits / chips are not capable of sustaining the data rates necessary for CD playback over a 1 meter cable in a controlled environment, and therefore there is little sonic degradation based on the digital data being lost or changed between transport and DAC.

Pops or anybody: Is the Illuminati D60 the same as the currently advertised Illumination D60? I have been watching this thread, but have nothing to add as I will be purchasing my "first" coaxial cable shortly to add a Bel Canto DAC to my system. I have been in contact with the Cable Co. in regard to 1.0 meter IC's, but now am consisering a 12.0 feet IC, which will allow me to shorten my speaker cable runs (I could then place the DAC and amp very close to my speakers). If anyone has tried 12.0 feet (4.0 meter) coaxial 75 ohm cables, I would also appreciate comments on your experience. Does the added length degrade the sound?

Ask and ye shall receive. Frogman set off my BS detector. I'm open minded here and do no want to attack anyone personally, but a family resemblance suggests that the listener is projecting a family persona on the family members. Because the job of a digital cable is quite different from the job of an interconnect or speaker cable. If an interconnect rolls off high frequencies, will its digital counterpart also roll off the JUST THE BITS THAT CARRY THE HIGH FREQUENCY INFORMATION?