Hi @FrancesL, welcome to the Sonos Community!

With Sonos surround setups you’d need at least three speakers: one to control the left, centre, and right front channels and two surrounds to cover both the left and right rear channels. The Amp and In-wall speakers cover the front channels, but a single Play:1 will only repeat what the Amp is playing and wont provide any surround channel audio. If you’re limited with space, then my suggestion would be to use speaker stands or wall mounts positioned behind your listening area and creating a Home Theatre setup in the Sonos app, that’ll give you the best listening experience for both TV and music.

If you’re not able to use stands or mounts, then there are a few options on how we can proceed with your current setup. I’d suggest swapping the Play:1 with another speaker such as the Era 100, Era 300, or Sonos Five rather than adding another speaker in that corner. The Era 100 is an easy upgrade over your Play:1 (and an upgrade over the Sonos One speaker) due to the extra tweeter. If you think your sound experience is barely lacking, then the Era 100 is a good choice.

If you think you’ll need a lot more, then you’ll want to decide between the Era 300 or Sonos Five. One of our regular members, @AjTrek1, has a great thread on the Era 300 vs the Five, which I’ll link below to help you decide. Granted, the thread is for general music listening, but as you’re using in-wall speakers and don’t have any Dolby Atmos capable speakers, I think the thread still applies:

Regarding the Move 2, I think the location you’ve selected is good for covering the dining room and kitchen. 

This is different to what is usually suggested and I don’t think the balance will ever be perfect since you have an atypical setup, perhaps a community member also has a few suggestions, but I hope the information above helps!

Thank you, @Jamie A! 

I may not have been clear enough that I am looking to replace the Play in that corner (not add another speaker with it). I was thinking an Era 300 or Sonos Five could be my best choice so will read the thread you mentioned. I am still trying to understand if the ability of the Five to automatically separate left and right channels provides any advantage over the Era 300 in my atypical setup. I forgot to note and need to consider that this room has 10-foot high ceilings.

Due to the layout of the room and door placement, it is not possible to fit two speakers behind the listening area even if I did wall mounts or stands. I’ve definitely looked at this carefully. I know I can’t get perfect balance but am trying to get the best option.

What the poster was trying to say is that if you “only want one more speaker by the Sub to help with the TV sound and music”, it’s not going to work well for TV.  The only way to incorporate a single speaker to a TV source is to group it with the TV speaker, as opposed to surrounds, which are bonded by a very different process.  A speaker grouped with a TV source is going to have a delay of about 75ms, causing an echo (amongst other problems), whereas surrounds are not delayed, and will play the surround effects. 

I did not set up the TV and Sonos in my new house, but the TV sound appears to be coming purely through the Amp, Sub, and in-wall speakers (and not at all through the TV speaker). When I turn on the TV and Play, I don’t hear a delay or echo, but I’m not an audiophile so may be missing it.

Those would be bonded together as a Home Theater, which sets up a low latency private 5 GHz network between the Amp and Sub in order to keep them in sync with the video.  If you chose to add surrounds, they would be set up on the same private network and would have no lag.  However, you need to add two surrounds (or an Amp powering two passive speakers) as stated by @Jamie A above. 

The only way to add a single speaker per your wish is to group it, and grouped speakers will have a lag for TV sources.