As I understand it, 75 Ohm is the standard for digital cable. Not all interconnects abide by this standard. It may not be relevant for very short runs, but a dedicated digital cable will follow the 75 Ohm standard. Your ears will tell you if it is significant.
Important Interconnect Question
How detrimental is it to not have a digital cable connecting a transport and a outboard dac? I was sold a analog interconnect by a dealer with whom I have a long standing affliation. I'm a bit embarassed to be even asking this but i assumed I was buying a digital cable. I'm not a 100% positive but very suspicious. I'm going to check when I get home.