Matching digital input impedance of dac with cable

Thanks tplavas...that was question. Do I need to match the impedance of the dac and the cable...from what I understand of your response I do need to match the impedance...

You need 75 ohms. There`s a reason there`s a standard.

Since we're on the subject, I've seen DACs with 75 ohm inputs & others with 110 ohm inputs. Is there a performance difference between the two other than the 110 ohm input is easier to drive for a transport?

Newogger,
yes, there's a difference in the way the digital data packets are arranged, which doesn't have any effects on audio performance that I'm aware of. Plus the 110 ohm connection is balanced, which should offer an advantage, but then you have to consider the extra difficulty involved in creating a balanced (3 wire) cable with excellent performance characteristics.
Sorry you asked? :)

A balanced connection is no guarantee of better performance. The transmitting and receiving chips for balanced and unbalanced connections are not identical in every machine. Therefore the only way to determine which cable is best for your application is to audition them.
Good luck.