I am new in thread / a new member, but watching it for a long time.
I have had the same problem a while ago - ensure that your soundcard runs at 48 kHz or locked off , if not, comb filter effects happens (44,1 kHz).
The hint is missing in manual, Smyth company knows that.
S/PDIF Format is 48kHz/24bit, output is always operating.
Make sure that your soundcard operates in optical mode and S/PDIF, not in coax/ADAT or AES/EBU.
Thanks that kinda helped :)
I couldnt find any option to set my card on 48 khz but I did find an option creative called: Bit Matched recording after I switched the soundcard to recording mode.
Also i got sound now! Hope to post something real soon now, I dont really have music though, as I only watch tv and movies but I will see what I can find :)