Feature Request: Atmos in Groups

I think there’s some interesting things to consider on this point.   Consider a Sonos system where some of the rooms are a stereo pair and others are mono. Grouping these rooms together won’t mean you’re playing mono everywhere. I believe (correct me if I’m wrong), that the mono speakers are actually capable of carrying the stereo audio signal and passing it on to other speakers in the group.  They actually process the stereo stream and mix it into a mono audio.  It is the exact same music track played everywhere in the group.

I don’t think the same can apply with atmos audio.  The same exact song in stereo and atmos are completely different tracks. So the question is, can you have a speaker ‘mix’ an atmos track down to stereo (like it can from stereo to mono), and would it sound any good?  Seems like the answer is no.  However, I created an Amazon music playlist with atmos tracks and attempted to play them over stereo speakers via Amazon app (not Sonos, but that should be tested).  I’m not quite sure if I’m hearing only L+R of an atmos track, or if Amazon was smart enough to replace the atmos track with a stereo equivalent.  

The other factor to consider is that when listening to atmos TV audio via an Arc or Beam, you can play atmos in the room connected to the TV, while any grouped room will play stereo or mono.  What’s happening here?    Is your room only sending the L+R channels and leaving out the rest?  Is there a stereo version of the audio that the room doesn’t play itself, but can send on to the other rooms (pretty sure this isn’t the case).

Related to the point above, it’s important to know that when Sonos groups rooms together, one of the rooms is always the coordinator.  That coordinator is the speaker that retrieves audio from the source (TV, streaming service, line in, or local library).   If the room that is the coordinator leaves the group, a new room is designated the coordinator, except in cases of TV audio where the coordinator can’t leave the group and continue playing the audio.  So when considering atmos streaming audio, you’d have an issue if a pair of Era 300s was the coordinator, playing atmos music, and then left the group.  Your other speakers are not atmos capable.  Likewise, if a non-atmos capable room is the coordinator, you can’t add your Era 300 room and suddenly start playing atmos music. It gets really messy, really fast.

In a perfect world, all Sonos speakers would be capable of transporting an atmos audio signal, regardless of whether they can play it or not.  As well, every atmos track would contain a stereo version of the track so that one source can play everywhere, similar to stereo/mono.  Both of these things are unlikely to happen anytime soon.  Sonos older speakers just aren’t built to handle atmos audio streams.  As well, streaming services are not well motivated to create a version of the track that contains multiple audio formats, as it would only be useful in multiroom audio systems like Sonos.