What length digital cable?

I used the CAL Delta / Sigma with a 1/2 Meter Silver Kimber Cable (KAGC?? -- 180 1/2M retail). In my time with this setup I tried several other cables and could resolve minute differences in cable, but not in length (never went longer than 2M per others recommendations). The only cables I could resolve a difference cost $500 and above retail.... Never went with them because the $$ for change was too much. Got much more bang for the buck going with High End cables between the DAC and the Pre-amp.

I read some similar manufacturer propaganda to what doug mentioned, but I thought that the minimum length they recommended was 1.5M. They said that the digital signal would ring in the cable, and if the cable was shorter than 1.5M, the echo in the cable would interfere with the original signal. The 1.5M length was long enough to dampen the ringing or delay it such that it didn't interfere with the original signal. I don't remember their exact reasoning. I also found it interesting after having stated such, they still sold cables of 0.5M, 1.0M etc.

Panzercat's post is what I've heard as well, and it confirms what my dealer and I felt we heard after a number of months of empirical listening using different lengths of the same cable--roughly 1-1/2 meter lengths seemed to sound a little better. Kimber claims that .75 meter works as well as 1.5 meters for their KS2020, and that's what I've used from my DVD player for 24/96 discs with no problems I can detect. So who really knows....

Doesn't a lot of this have to do with the nominal impedance of any given cable?

...Specifically, it is my understanding that an increased length of IC has increased impedance (as seen by the components).

If one considers that as frequency increases so does impedance this would suggest a limit to the high frequency information that could be accurately transmitted via cables with higher impedances. So length might have more to do with characteristic impedance. I understand this to be true with data cables like cat 5 – Specific impedance parameters are supposed to be critical to the speed within a computer network.

Anyone else more versed on this? Would love to get the straight goods. I often see 75ohm or 110ohm impedance cables specified or recommended for digital. I have also read that 24/96khz has different cable requirements compared to 16/44.1khz. This also makes one consider what requirements would be for even faster bit-rates such as those found in DVD & DVD-A.