Is it possible that the input mode got switched to digital and it's looking for a digital signal all the time? IE. when a digital sound format is present it plays but it can't process an analog signal. The format should generally be set to auto so it decodes whatever type of signal (digital or analog) it receives.

See: Step 3 in the Batpig Denon guide
BatPig


2xM80 VP180 2xQS8 2xM3 HSU STF3 LG 60PS11 Denon 3808 ATI 1506 LCR 2xATI 1502 Oppo BDP-83