Sonos Arc, HDFury Arcana, LG OLED, Apple 4K

Midwested wrote:

[...]

I know Dolby Atmos is getting through since all channels I tested from the Apple TV+ channel show as Dolby Atmos in the Sonos app. But other apps ie. Amazon Prime, Netflix do any better than “Multichannel PCM 5.1” and many just show “Stereo”. Any advice is appreciated. Right now I’m thinking I bought a $200 brick.

So... you're saying that Atmos is coming through to the Sonos in some cases. Good. In your ATV4K, under Settings > Video and Audio > AUDIO: Audio Format, does it report "Auto, Atmos Available"? If so, the program audio attributes displayed in Netflix may not be a problem... in the User Manual 4K Arcana Rev 1. 20, there's an "ATV4K FAQ" section with the following paragraph:

Netflix on ATV4K only show 5.1 titles? One tip to save other Apple TV users some confusion, it may not say Atmos in the menu of the app (ex 5.1 in Netflix) you’re using at first, but as long as you see Atmos under audio settings, just begin playing content you know supports Atmos and the app will adjust. Prime Video and Netflix seems similar in this regard. As for titles we know have Atmos, Prime video has Jack Ryan, Netflix The Old Guard and Disney + the Mandalorian. Each of those is platform original and there for should be available in every region.  If you verify audio format with SONOS APP, make sure to restart it fully before checking.

Bummer that Sonos didn't provide a couple of HDMI 2.1 inputs on their soundbar...

Yeah - it's a weird one...

My own ATV4K is connected to a Sony soundbar with Atmos support, and while I recall seeing Netflix highlight Dolby Atmos with most programs (I dropped Netflix recently - didn't feel I was getting $20/month-worth out of it), and Disney+ reports Atmos for most, but I don't see Prime Video bragging about Dolby Atmos sound tracks...

Because the above FAQ entry referred to Jack Ryan on Amazon Prime as an Atmos title, I took a look at that. The Jack Ryan program info didn't say "5.1" or anything about the audio, but I started the first episode and sure enough, my soundbar reported playing Dolby Atmos 48Hz.