Hi All -- Thanks in advance for any ideas.
I have a Panasonic TC-P65ST60 from 2013, HDMI spec is "HDAVI Control 5" -- which is ARC and CEC compatible.
I get awesome sound through my Amp/Sub/pair of Sonos Play:1 setup -- but only when I use the Panasonic apps on the Smart TV. The Sonos app shows that the "Audio In" to the Amp is Dolby 5.1 in the "About My Sonos System" when I use it like this.
BUT -- I cannot get any content to play 5.1 from an external source -- not an AppleTV 4, a recent Amazon Fire Stick, or a recent Roku Stick. It always plays Stereo 2 channel from these sources, and that's what the Sonos app shows.
I set these sources up as inputs to HDMI 1 or HDMI 3 on the Panasonic TV. (HDMI 2 is the ARC port).
I've tried all the settings I can access on the TV menu tree, and nothing changes the output. When I force the source (any of the three I've tried) to go Dolby 5.1, there's no sound from content at all -- there is user interface clicking, but no sound playing content.
CEC works; the TV turns off when the source streamer tells it to, when it sleeps.
Any ideas? Is my TV too old to do the passthrough accurately? The TV firmware was last updated in November 2014, and my set is current with that version.