The first drawing, you would need two Amps, front and surround.

I'm not a ceiling speaker fan, ear level ones sound much more natural to me. Era-100 surrounds would be a good choice, in-wall might be good too if there is no space.

Hi Stanley 

Thanks for the reply and info on set up requiring 2 amps didn't know that and it may rule out that set up, I do currently own the beam and one speaker so could upgrade this with another one speaker (or 2 era 100) and a mini sub to complete home theatre set or would I require an amp for all this to work aswell? 

Just wanting to double check before a purchase anything and end up needing more speakers/amps to make it all work. 

@Tomachek 

You can use the Beam for the front Left/Center/Right channel audio and the Sonos Amp to drive your rear left/right (surround) ceiling speakers but like @Stanley_4 i don’t like ceiling speakers but it would be okay for surrounds - I too though would go with two One SLs/Ones/Era’s for the rear channel audio set at head height.  I would definitely add a Sub to the setup too, but that can always come later.

For surround duties, an alternative but cost effective solution, could be a pair of Ikea Symfonisk bookshelf speakers. They are still Sonos speakers, just inside an Ikea case.

Ikea sell both floor stands and wall brackets suitable for them and once added as surrounds and trueplay ran, I’m not completely convinced the premium for Ones/Eras 100 is worth it when used as surrounds.

If buying new then

£230 for a pair of Symfonisk + either floor stands at £58 a pair or wall mounts at £38 a pair

vs

£500 for a pair of Era 100 + stand or wall mount cost

Some people use the more expensive Symfonisk picture frames for surrounds as they are wall mount and don’t stand out as speakers.

Everyone has different preferences, but I thought it worth suggesting as an option.

Room size-wise, you won’t have any issues. When I wanting to reduce my speaker count I was testing a 4.1 setup. I used an Amp for the fronts, paired to Symfonisk lamps as the surrounds. My room is 5m x 3m and volume level was definitely not a concern. I needed to leave the room long before I reached 50 in the Sonos app volume control. 

Ultimately, for my HT I ended up back with the same number of speakers I started with, but as 5.1.2 instead of 7.1 

Thanks for the info Ken gives me something to think about before I make a purchase. My only concern with using 2 one/era speakers is my door for access to the room is at rear left(back wall) so I may need to use wall mount and have it above door frame. Sigh has gave me another option with the IKEA speakers so I'll have read up on this as I didn't know this was an option 

Thanks 

Thanks for the info Sigh as I didn't know about the IKEA speakers so I'm glad I asked. I'll need to read up on the picture frames as they might be best option as I have a door at left rear which may hinder my rear speakers sitting in both corners. Plenty to think about before I decide what to do,

thanks again 

Perfect placement** isn’t essential for the surrounds, mine are in very poor locations but still sound pretty good. 

With the picture frame option you could use some 3M Command hangers that allow you to easily reposition the speakers with no wall damage.

** The 300s really need to be well placed (from reading here, not personal listening) to make them worth the extra expense.

3M - https://www.amazon.com/Command-Picture-Decorate-Damage-Free-PH206-14NA/dp/B073XR4X72/ref=sr_1_1_sspa

Thanks again for the advice Stanley, much appreciated