Living area

This could be done, though your “home theatre” Sonos “room” would only consist of two speakers (fabricating a phantom centre) from Amp 1. Amp 2 would be a separate “room” in Sonos that can be grouped with Amp 1. You could also set up Amp two as surrounds to Amp 1 (bonding the Amps to form one “room”). For music they will play stereo from all four speakers.

Open plan

If you set up the system in either of the ways I’ve described, that’s the use you’ll get. You cannot use the system for both E-W and N-S orientation. I’m not sure the Amps will do mono too.

Thanks for the reply. I have a couple more questions based on your feedback.

Living Area.

For home theatre setup in this part of the space. I believe I can add a sonos wireless subwoofer. Rather than having AMP1 front speakers acting to produce a phantom centre -is it possible to also use either a beam G2 or other suitable sonos wireless speaker to be an actual centre channel and speaker? True 5.1

Open Plan.

What are your thoughts on potentially using a smart audio switch like Audioflow to crosswire the array of 4 ceiling speakers across both AMP 1 & 2? Then use the smart switch to switch stereo pairs from N-S to E-W orientation? (I’m curious now, not sure I’d bother with the effort it even if it were workable...)

Sonos has no function for a single speaker of any type to be a ‘center channel’. If you use an Amp, you get the ‘phantom center’, if you use a soundbar, the discrete center is included with the discrete right and the discrete left. 

I have no experience of the set up you propose as optïon 2. Maybe someone else can help you on this.

Yes, AMP can be set for mono.

However, I think that this will quickly become an unwelcome chore. You can configure a pair of AMP’s and a SUB or two into a home theater surround system, but you would need to break down the surround system before you could switch the AMP’s to mono. This teardown, switch each AMP to mono, then reverse the process to rebuild the surround system for movies will take some time and become boring very quickly -- especially if a SUB or two are in the surround system.

I think that you would be better served by enlisting a 3rd AMP and four ceiling speakers in the N-S area. Be sure to include separate Volume controls for each pair of speakers. This will allow you to keep the surround system intact and would cover the space more uniformly. I also suggest that you alternate left and right speakers in the N-S area, rather than having a left and right side of the room.

Your space is large enough that the speed of sound may become an issue. I say “may” because individual sensitivity to this varies. I assume that the TV will be located at the far end of the E-W space. Sound is pokey, traveling at about 0.3m per millisecond. This means that SUB placed in the proper location for movie surround will be about 17m from a listener at the far end of the N-S space. In round numbers the bass will be about 50ms late for this listener. Some listeners will be very annoyed by this while others will not. You could minimize this issue (notice that I did not say “eliminate”) by adding a SUB to the N-S area and not placing it at the far end of that area.