Apologies for resurrecting this old thread, but has anyone had intermittent issues with this DAC struggling to lock onto an optical signal? The display shows the sampling frequency e.g. '44.1' mostly, but every now and then the sound cuts out and then the display changes to 'N-LOCK' - which I assume means 'no lock'.
P.S. I have tried 2 different cables, and 2 different sources.