I replaced both cables and tried a different source input on the TV. No fix.
So, I ordered a splitter. No fix.
I factory reset the Denon. Fix.
This was on Friday.
Then this morning I go to watch the latest "GOT" on the TV in the kitchen. Apple TV into Denon AVR-1613. Starts as normal, gets to beginning of programming and screen goes blank.
I move to the sunroom. Apple TV into analog Pioneer Elite. Starts as normal, meaning I get the opening HBOGo logo, and the Nudity warning, then the spinning wheel, then black.
Soooo, I go downstairs to the set-up mentioned above. Same problem. I'll fiddle with it some more this afternoon, but obviously very frustrating.