While a digital signal is just that, digits and not sound, it easy to conclude that any 75 ohm cable will do. But quality does matter in a high end system and it has to do with speed and timing of the signal. It has also been found that a lot of CD Player / Transport outputs and DACs inputs are not a perfect/true 75 ohm, so the cables impedence might be off, but right for your system, so try a few if you can borrow them. The impedence may also change slightly over the frequency response range 20KHz ot 20MHz Stick with Coax over Optical on most applications.
