Jeff, if you determine it has no useful life for you, and Denon is not going to help, drop me an email. Might be something I would want to tinker with.
JohnS
Before trashing it, check yor X.1 inputs to see if the amp is still useable. Not locking onto a digital signal does sound like a dsp issue. If you can get the analog inputs to work, could serve some use.
JohnS