Being digital, audio quality wise, what you need to listen out for is pops/clicks/squelches lke you get from a dab radio or digital TV if its not got a very good signal, this means it doesnt have a good digital clock sync, if you dont hear anything like that (most ofen just the odd pop) then your cable is good enough.
Hell, several times ive even used one side of a normal analogue hifi stereo RCA cable when i couldnt be bothered to dig out an spdiff cable and its worked fine,