Why do digital cables sound different?

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.

Redkiwi, I am not a designer of digital audio playback devices but I thought that the data sent to the DAC is asynchronis. If that is true where are the timing errors? Is the data clocked from the transport to the DAC or is it really asynchronis? I do not know, but if it is asynch, then the statement about arriving with perfect timing does not make sense to me. Is it the timing between bits that you are talking about? If that is the case, how can the cable change the timing between the bits or even cause jitter?

Redkiwi, even if jitter did cause a problem, I do not think it would manifest itself in harmonically related distortions. I can't see it causeing either higher or lower order distortions.

Actually, Redkiwi I captured a megasample. I had a meg of aquisition memory and I filled it. After I filled the 1 meg I ceased taking data. The test took 80 minutes for all the data to be captured (106 bits every .5 sec [5 16 bit patterns plus the placeholder pattern]). I captured 16960 patterns or words if you will each 16 bits long.