Though a SPDIF cable really ought to be 75 ohm coax, in practice the proverbial "piece of
wet string" generally works fine! I'm not sure your cable will be any closer to the
correct spec. than a cheap hi-fi cable, and a standard soldered phono connector, when it
won't be subjected to physical stress, does the job just as well as a fancy one.
What exactly is the "etc." part of "drop-outs etc."? You may have a damaged cable. But
could you have a clocking issue?