Why do digital cables sound different?

I second Mapman's recommendation of network streaming. Computer speed, amount of RAM, playback program, file format etc. make no difference since timing is recreated on the other side of the bridge (saves a lot of money). Sound still can be affected by ambient electrical noise but in this respect slow computer might be better than the fast one.

Asynchronous USB should be good as well since, as name suggests, it does not use noisy/jittery timing from computer by buffering the data and requesting different amount of samples each frame to keep buffer between underflow and overflow.

YEs, asynchronous USB is the other key technology, especially I think if a general purpose computer is the source for streaming to DAC and maybe also if one wishes to push the limits in regards to high resolution digital audio files in that this is a newer technology than traditional SPDIF/TOSLINK. Maybe.

Mapman, you are testing my memory. I believe they were all 1.0 m and all in good condition. The brands were Elco, Legend(?), Virtue, Monster, and some unknown cable. The Elco was the best.

Kijanki, let me make sure I am tracking with you. You are saying that jitter is important. That jitter can also result from cable induced errors. That re-clocking at the DAC does not necessarily correct for all/any errors related to jitter that could occur during delivery of the raw digital signal through a cable. Does it follow that some digital cables are better at delivering digital signals free of or with less added jitter?

On a related note, in theory or in measurement, can a digital signal be corrupted in a cable, say due to exposure to strong EMF, to the point where 1s and 0s are actually deleted or unreadable at the DAC. I.E. outright data loss?

"Does it follow that some digital cables are better at delivering digital signals free of or with less added jitter?"

I cannot speak for K. but clearly there are always differences between two products. The question is more how much these matter in practice. I tend to think that any good quality product will deliver excellent results for most people in most cases. There are probably always exceptions though.

"On a related note, in theory or in measurement, can a digital signal be corrupted in a cable, say due to exposure to strong EMF, to the point where 1s and 0s are actually deleted or unreadable at the DAC. I.E. outright data loss?"

That's a good question. Of course it is possible. DIgital gear is inherently a source of noise and may be affected as well. I think the former is a much bigger problem than the later. I encounter it to a great degree with my setup. Noise control is important. SOme wires may shield against it better than others and I think that can make a difference in most cases where detailed listening is involved.