Carl - yes granted I was quick to jump to a conclusion there. I suppose as it only appears to have happened after the upgrade I assumed that must have been the case.

Ian - unfortunately due to the location of my Mac (desktop) it's a real pain to feed a wire through to it so haven't tried wired. I've started the new backup now so may try it a later date if I have this problem again.

DSP5200, ifi Zen Stream, 218, Tidal Connect