Except for optical cable, to an extent even a digital signal on a copper wire is susceptible to noise. If the signal is uni-directional noise in the signal will corrupt the output. If the toslink was bi-directional in the sense that when an error is detected it sends back a request for retransmission of the affected bits, then there would be little disruption and distortion but this is not the case AFAIK.

I've used 120V electrical wiring for speakers and for the most part it is fine. However, 120V electrical wiring is stranded and there are air gaps in the stranding that could create problems in the signal.

Calvin