Digital Cable Question

75 ohms is the primary reason. The impedance match allows less reflections inside the cable and thus less 'jitter'
On another site a comment was made about length. At least one site offers two lengths: 12 inches, or 5 meters!!
Which apparently are the best lengths for less reflections being a problem.
Also 'special' connectors.
Well I happened to have an Audioquest 'true 75 ohm' cable with that sort of 'snap on' connectors (from junk pile at local store $3 it was used for a video cable) except mine is 25' long. Well I stuck it in anyway and HEY! better high frequency for real.
I may just go ahead a get one of those in a five meter length.

I'm using a Clarity Cable XLR as a digital cable and it smokes my JPS Superconductor Q and Morrow DIG4 AES/EBU. Soundstage is more defined and precise.

At least one site offers two lengths: 12 inches, or 5 meters!! Which apparently are the best lengths for less reflections being a problem.

The usual recommendation, if the cable is not very short (less than 12 inches) is 1.5 meters, or about 5 feet. See this paper.

Length beyond 1.5 meters would not provide additional benefit in terms of reflection timing (unless perhaps the output signal of the source component has unusually slow risetimes and falltimes). The additional length could, however, conceivably result in increased noise pickup from ground-loop or rfi/emi effects, thereby worsening jitter. Also, if hi rez formats are involved a 5 meter length could actually cause reflection timing to become more of a problem rather than less.

These length recommendations, btw, are generally intended to further improve the situation where a reasonably good impedance match exists to begin with. A severe mismatch will not necessarily be helped by using a 12 inch or less cable length.

The 1.5 meter length probably would help a severe mismatch in the case of redbook data rates, but not necessarily for hi rez rates. In the case of hi rez data rates, if the impedance mismatch is severe enough, reflections corresponding to a given signal edge (i.e., a given 0 to 1 or 1 to 0 transition) may keep propagating back and forth across the length of the cable enough times to cause distortion on the following signal edge.

Regards,
-- Al

Thanks for all of your kind replies gents, they were very informative.