Do they come through losslessly via the ATV then? Atmos directly on Sonos is of course lossy compressed.

I am not certain. Even though the Apple TV 4K uses Dolby MAT which outputs lossless PCM audio, I’m pretty sure Apple Music still streams Spatial Audio/Dolby Atmos music using the Dolby Digital Plus JOC codec. Regardless, I think Dolby Atmos music sounds really great on the Apple TV, and the audio quality has actually improved over time. I remember hearing a dramatic improvement after a tvOS update earlier this year. I have also compared the same music on Blu-ray disc, and on some albums/songs I actually prefer the Apple Music stream over the lossless Dolby TrueHD/Atmos version on Blu-ray.

Add these albums to the great list above:

Rush “Moving Pictures” 50th Anniversary

Megadeth “Rust in Peace” Remaster 

Yes “Mirror the Sky”

Love Steven Wilson’s Atmos works. And enjoy watching rolling credits at the end of Atmos films with scores mixed discretely in Atmos!

I too use the AplpeTV Apple Music app.

I have noticed a lot of Atmos album mixes with very little bass, including all three mentioned albums above (not so much Steven Wilson’s stuff). Mirror the Sky has like nothing below ~150 Hz.

Have to add about 10-15 dB gain to my subs but even then it is just exaggerating what little sub 80 hz information is available. So I guess more accurately it is ~60-125 Hz zone that feels empty on a lot of these Atmos album mixes.

And it’s not my room or setup, which has been acoustically treated, decoupled from the rest of the house, and sonically calibrated. All else sounds amazing.

Have you listened to Steven Wilson’s new album, The Harmony Codex in Dolby Atmos yet? It is definitely one the best Atmos mixes ever created.

https://music.apple.com/us/album/the-harmony-codex/1694731770

No I haven't listened to it! Already putting together a listening party with some fellow SWilson nerds will report back.