No HDMI out from 4K 85" Sony

My Denon has a port marked "eARC" that helped.

Any recommendations for a 20' optical cable?

With copyright and piracy laws changing constantly the lawyers have more to do with technology being released than the engineers do. If you are stuck in some kind of "hook up" middle ground look into a company called HDFury they definitely have what you are looking for including ARC/eARC, good luck. Cheers

@dbphd I recently had to deal with this same issue on a Samsung TV. The solution was to turn off all the CEC/eARC toggles, then turn them back on again. There are two toggles in the "Audio" section and one hidden in the "General" section of the Samsung TV settings. That last one was the reason this project took me way too long.

I ultimately prefer HDMI vs tosklin for audio out from a TV because the former allows me to use one remote to power everything on/off, adjust volume, and search for content. I have 3 devices (video streamer --> TV --> audio system), and I love using the remote from the video streamer to control everything.

I may have found just what i need.  It appears as though a $50 device from OREI takes in eARC from a TV and outputs HDMI to a non-eARC processor.  That seems too good to be true, but I'll try it.