John,
Thanks for your response but it misses the point of my question, likely due to the poor wording of my question. I have a Sonos Arc that supports Dolby Atmos and 4K TV that does. My Roku is connected to a sound extractor which sends video to the TV and audio to the Sonos.
When I go to the digital output format menu my current Ultra, I am presented with 4 choices - auto, passthrough, stereo, custom. I use 'passthrough' for the Sonos which decodes Atmos.
I bought a Stick solely to eliminate a few cables. I only bought it after reading on the Roku website that it >>Supports pass-through of Dolby-encoded audio over HDMI<<. When I connected the Stick to my sound extractor and went to the Roku output format menu, the choice 'passthrough' is no longer present. Where did it go?
Roku's tech support has been less than stellar. I called and while speaking with someone was disconnected. I called back and spoke with another person who said that he would elevate my question about passthrough and promised a follow up email within 24 hours. Didn't happen. So I posted here.
The whole question is moot as I returned the Stick and reinstalled my Ultra. Does Roku monitor this forum?