Why do digital cables sound different?

First - the digital datastream carried on a coax connection is an analogue signal, albeit used to represent 1's and 0's. Second - I have never seen a signal coming out of one of these cables on a scope that is a perfect square wave. Third - lack of perfection in the square wave means jitter. Fourth - jitter produces harmonic distortion in the output of the DAC, different forms of jitter distortion producing different harmonic signatures - some sounding soft, some sounding harsh. Fifth - I have never heard or measured a reclocking device (including the Genesis Digital Lens) that does not reveal some of the jitter distortion created by upstream cables and components. And what is more important is that digital cables do sound different, provided of course you have a high resolution system and sensitive ears. I am intrigued however about the observed phenomena of a cable's sonic signature when used as an analogue interconnect, being present when used as a digital cable. I have heard this too, and with cables other than Kimber, and I reject the placebo argument in the context of how I test components. I find this one harder to explain and can only surmise that we cannot look at interfaces between components as separate systems, and that each interface may leak artifacts of itself into other parts of the total system. The active devices that buffer interfaces are meant to deal with this, but perhaps no real world electronic part works exactly how it is designed to work?

Even with perfect square waves there will be jitter in a clock recovery circuit, due to the stochastic nature of the bit stream. Buffering the data and reclocking with a nice stable clock avoids the jitter problem, at the expense of some relatively long term drift in average sample rates to accomodate changes in the data transmission clock rate. If done properly (i.e., large data buffer, low loop bandwidths), then the time constant would be on the order of seconds. A $49 Discman CD player with "skip free" circuitry does this. So does my Levinson 360S. Now we just have to get audio manufacturers to work on the price points in between. :-)

For some reason all of these explanations are never good enough for some people. This topic inevitably leads to a long debate. Science tries to explain an experience and often falls short. All I need to know is that I tried 5 different coax cables and they all sounded different. One was consistantly better than the others, and I bought it. Anyone who can't hear the difference needs work on their listening skill.

Hear Hear.

My experience is that there are definite differences between digital cables. I suspect it has more to do with the interface of the plugs and sockets (particularly w/ RCAs) than it does with the cable itself.