It’s only been a day with the Era 300s, but something I sort of picked up on with the Arc setup that stands out a lot now that I have two atmos capable rooms.  I can’t use my multroom audio system to play atmos music in multiple rooms very well.  The minute I group a non-atmos room into my atmos room, I lose atmos music where it can be played.  Lowest common denominator.  Sure, I could eventually add more atmos rooms, but many spaces will never makes sense for atmos.  Bathrooms, garage, outdoors, etc.

I think I understand why this is the case. Atmos tracks are complete different than strereo tracks...a different file is being played.  Where as you can ‘extract’ mono from a stereo track for mono only rooms, You cannot do the same with atmos and stereo.

So, what is needed is an audio format that contains a track in atmos and in stereo with all audio channels in sync.  With this, your atmos capable room can play atmos audio while your rooms that are only (only?) stereo/mono capable can play stereo/mono.   And since I don’t think other streaming services have that much motivation for an atmos/stereo format since there target audience isn’t primarily multiroom audio, it makes more sense for Sonos Radio to tackle this along with Sonos.

As a bonus feature, if you don’t care for a particular atmos mix of track, give the option to switch to stereo.