Okay, I've been fiddling with this today and may have some up with something. I'm swapping thru different optical cables to see if that makes a difference. Yeah, I did this before. No real differences.It seems that the only variable left might be your optical cable. Have you tried another one? It's odd that the one you have works with Bifrost and not with the Syn optical input, but I suppose that's possible. I think that would be the next logical troubleshooting step.
My television is on and muted but the optical is still active. However, this time I'm sitting right beside my right channel speaker, ear level, and I'm clicking thru the SYN inputs. USB > Optical > Analog, over and over. As the lights/selection land on Optical, I'm getting a fraction of a second of sound thru that right channel speaker. Remember I said that the USB & analog inputs work fine. Could the issue be the switch or possibly a bad solder joint at one of the switch's terminals?
Schiit repair said, "Syn has output on all sample rates 44.1 - 192K." I don't have any idea where they were measuring 'output.' I've sent them an email explaining this so we'll see what happens next week.
Thanks for the reply Tbone.