The Arc is not recommended to be mounted above the TV; if wall mounting. That aside the Arc is designed so that its upward firing speakers reflect off the ceiling while its side firing speakers reflect off the side walls. 

Click this link  for proper wall mounting of the Arc

You would want to use the wall mount designed for the Arc in this link.

The Beam2 is also recommended to be mounted below the TV. Click here for proper wall mounting of the Beam 2. However, the Beam2 may be a better choice since it does not have upward firing speakers to be concerned with. The sound is projected in a more forward manner.

Besides the Sonos wall mounting instructions...the preferred position of the sound bar (wall mount or not) is below the TV so as to keep the dialogue anchored to the view (TV) screen.

As far as the Beam2 versus the Playbar since all of the Playbar speakers are forward firing your experience may be better than with the Beam2. It really comes down to what sounds best to your ear. 

If your main concern were to enjoy Dolby Atmos content I’d recommend the Beam2 without hesitation. As it stands you have other considerations as well. 

Adding the sub will improve your listening experience for the Arc, Beam2 and the Playbar. The sub relieves the soundbar of low-end frequencies allowing it to process the mids and highs unencumbered; especially dialogue.

Maybe get the Arc, then move the TV up a bit to allow the Arc to be mounted below it. Put the Arc on a shelf that allows it to be placed far enough in front of the TV to meet the suggested mounting position.

Instead of a shelf, you might like the looks of an extendable wall mount that you could pull out when in use and push back nearly flush when not in use.

I have several Beams and love them but when filling a bigger room the Arc is far better. I also find the stereo imaging much better at my usual listening distances due to the Arc’s greater width.

If you are happy it is a lot of work/expense to change just to have newer kit.

Thanks for the replies and the suggestions

It’s not really possible to change the current set up or positions of the TV and playbar

I’m a bit new to Dolby Atmos, but on further reading, I’m not sure we’d benefit that much.  We don’t use streaming services like Apple TV, Disney, Netflox etc. and mostly watch TV programmes with the occasional film. I read that the benefits of the upward firing speakers is the sound height, but we’ve kind of already got that with the playbar where it is.  I do remember a film scene with an airplane flying overhead, and it did sound like it was flying above us

Any change to an Atmos compatible soundbar is also going to mean routing a new cable behind the recess wall; doable but not straightforward

So I’m thinking for now, I will just add the sub - it will be better than now. Yes, the beam or arc will be better still, but is it worth the money and the hassle?; probably not

You’ll love the improvement the Sub gets you and it works for all sources, not just Atmos ones.

Be sure to try it in several positions in the room and go with the one that sounds the best, considering of course spousal preferences on room arrangement. :-)

HI

@DavidJS 

I think you’ve made the best decision based upon your current room environment. I don’t know the exact layout of your room but since you’re adding a sub you might consider going full “monty” and add two Sonos One’s to experience surround sound. The surrounds will provide ambient audio for any show with DD 5.1 (Dolby Digital) audio which is common for a lot of streamed and OTA viewing content.  Just a thought 

Thank you both

I do have two Play 1s as rear surrounds

Both the Play 1s and the Playbar are from 2016 - I presume I can still pair the Sub Gen 3 with them?

Yes! (I assume you are running the S2 app).

Below is a link to the Sonos page that shows speaker compatibility with S1 and S2 apps

https://support.sonos.com/en-us/article/sonos-s2-compatibility

Yep, running S2 for all but one of my products

Have a separate S1 set up for the older, standalone Play 5