Hi @mmducharme
Welcome to the Sonos Community!
It’s not clear where you plan to sit in the great room, but given that the walls you plan to mount the surrounds on are perpendicular to the wall with the TV, I would recommend a pair of One SLs on wall mounts (or stands), behind the seating position and angled in towards it.
Any In-wall speakers will be unable to angle towards the seating position, so I doubt their relative ability to successfully recreate the soundstage. The Sonance In-wall speakers are great (as is the Amp), but I think One SLs would produce a better effect in this room.
It’s unfortunate that the Atmos height channels may have trouble bouncing off your vaulted ceiling, but Arc is still a good pick for a room of that size.
I hope this helps.
Agree with Corry no this. Some in-wall small speakers allow you to aim the speakers , which will help focusing the sound on the seating area, but One SLs would give you a lot more flexibility.
Rear surround sound does not require really great speaker quality in general, since it’s essentially background audio, not the main sound stage. One SLs, are ideal, maybe more than you need for that. Likewise, if you do prefer in-wall speakers, the Sonos/Sonance speakers would be more than enough for the requirements.
I second @melvimbe and @Corry P Moreover I would suggest to foresee Ethernet cable wiring between the location of your router (and/or switch) and the SONOS devices.
Thanks everyone for the great feedback.
To be honest I was actually surprised to see the preferred speaker is the One SL. I had assumed the One SL when compared to the AMP & Sonance in-wall they would be at least equal (even thought the Sonance would have an edge above SL One). Certainly gives me something to think about. I prefer the look of the in-walls obviously as they are recessed and relatively invisible- but if the SL’s are truly a better choice I may need to re think some things.
-Matt