The specification from the client was, "I need some way to hear my TV better that doesn't blow out my wife and kids sitting alongside me also watching/listening [to a 5.1 surround system]." The technical reality is that there's not a [cost effective] way to add duplicative analog or PCM-Toslink feeds from remotely-located source equipment to this Denon AVR, all of which output Dolby Digital encoded audio to the AVR via HDMI.

As such, I need a device to take a switched, muxed output of the AVR and convert or transcode it into some format that can be fed to a set of wireless headphones. I asked about toslink/DD inputs specifically because SONY once made a set of wireless cans with DD-capable Toslink in, but they were long ago discontinued.

As suggested by Fred Harding, an HDMI Audio De-embedder on the AVR's Zone 2 HDMI output feeding a set of wireless cans with stereo inputs may be the best solution.