I don't know if this response has been given before but this is what I know. For digital signal paths the frequencies of concern (pulse rate, pulse edges, etc.) are outside (higher) than the normal audio domain. In fact, they behave more like RF. So, the digital cable is essentially a specialized RF cable. At RF frequencies it is the cable impedance, especially at the interfaces (connectors) that is important because mismatches with the commected components can cause signal reflecttions. What this means, obviously, is that phantom bits may been ADDED to the digital stream. So, a good quality digital cable is just as important, if not more so, than your analog interconnects!