Why do digital cables sound different?

One more thing. The rep rate of the bits in each burst was 10KHz. Ok, I should have set the rate to 40KHz, but I still doubt I would have lost any data as this is a pretty low frequency for these cables or at least 2 of the 3 cables.

Multiply that by 16 bits per word Gmkowal. I guess for the fourth time, the issue is not dropping bits, but that timing errors (not bit errors) cause harmonic distortion at the output of the DAC chip. Your investigations should focus on this phenomena - ie. varying the jitter at input (while leaving the bits the same) and measure the change in harmonic distortion at the output.

I'm still missing something, but I've been known to be dense before - my take on timing errors would be that they cause bits to be misinterpreted - since sender and receiver have subtly different experiences with their independent clocking mechanisms, the receiver interprets things slightly askew and gets a different "answer" than the sender sent. The result would be different bits fed into the DAC than if there was a perfect transfer. Is there something to "timing errors" beyond this that I'm missing?

Now you have got me Kthomas - I don't know, and have not done much work on it since I cannot change how DACs work. I have only got so far as observing how transmission interfaces are subject to jitter and how jitter results in harmonic distortion. I suspect you are not quite right about the DAC getting bits wrong and it is more about how the DAC converts the digits to an analogue wave-form and how this is upset by timimg errors in the arrival of the digits. I surmise that the DAC cannot construct an accurate analogue waveform from a datastream containing jitter errors without a perfect buffering system. One can imagine how with no buffering at all, a DAC would find it difficult to create a perfect analogue waveform with digits arriving with imperfect timing. When I add to this the fact that I have never heard a buffering system that eliminates upstream jitter (they just reduce it or change it), then I can intuitively imagine how the problem arises. If I understood more about how buffering systems fail to work perfectly then I might have a better answer.

On someone's reccomendation I purchased a RadShack Digital RCA cable. They claimed it was very good, it was so bad there was audible static. I worked with an engineer once who screwed up the implementation of my DAC driver that it was always 2 bits off on each word. This causes the static. On most protocols I've workrd with, if they don't sync up they just drop the data. I assume that the thought here is dropping a sample here or there is no big deal. I'm pretty sure they didn't realize how audible the inadequacies were going to be. If they really wanted to do this right, they should have gone with laser pickup on analog discs.