home theater

Hi

To be clear the overhead speakers would not mess up Dolby Atmos.  Prior to the Era 300’s…Sonos One’s or any Sonos standalone speaker pair (except Move, Roam or Sonos Play 5-gen1) were used as surrounds with the Arc.

The Arc still delivered Dolby Atmos sound but it wasn’t entirely as immersive pre-introduction of the Era 300 series. I used Sonos One’s with my Arc and was able to enjoy Dolby Atmos. I have since replaced them with Era 300’s.

However, Dolby Atmos or not in-ceiling speakers are not the go-to speaker for surround effect. The listening position is critical reference the seating placement. IMO, if rear speaker invisibility is of utmost importance I’d opt for Sonos In-wall speakers. The Dolby Atmos effect would still not be the same as with Era 300’s used as rears; but no worse than using Sonos One’s.

As you moved into a house with the two rows of in-ceiling speakers I suspect the previous owner used a traditional surround setup with separate left/center/right front speakers, sub and amp which yielded 7.1 surround. Sonos is not designed to duplicate that type of setup. You might want to consider a traditional 7.1 surround setup and possibly consult a professional installer.

Downward firing Surrounds means no separation from the height channels (in-ceiling or up firing), you are wasting your money trying to achieve Atmos if your Surround and Rear channels are in-ceiling.

Assuming your are creating a long term solution I’d outline what you want to achieve, the available budget, the room seating layout and ignore any preinstalled speakers, I’d avoid a long term compromise to make use of badly placed ceiling speakers.