No surround speaker will change the balance in favor of the beam if you find it lacking. 

If you see effects heavy movies, a sub will make a big difference, but it is expensive, so try one on a returnable basis.

Ok thanks. Just so clear you reckon go for surround speakers or just get a sub to try first?

The sub first. The surrounds will enhance but the sub has the greater chance of tilting the balance.

Ok thanks for your help. My LG tv has Dolby Atmos. Pretty gutted the beam didn’t have that. Would have needed to get the arc which is double the price...

But then isn't arc better than beam plus sub on price?

Why not try both and return what does not work as well on a value for money assessment?

I have no interest in stuff like Atmos and I don't know if that is the reason for what you are saying, but the comparative testing should work regardless.

Yes the arc would be better value than beam plus sub. Think will struggle to send beam back now even only a couple of days old as got rid of box. Unless can get hold of an empty box from anywhere. I was fairly confident would be perfect given the reviews I read. Why does Atmos not interest you? Can you get that experience still without that?

All my TV audio needs continue to be well met by a stereo amp getting signals from the TV and driving two good quality speakers flanking the TV from some distance away on either side. 

I have never been too fond of the bar idea that cannot deliver the spread of sound that a separated speaker pair can, and good speakers can also do bass a lot better than any bar that does not have a sub attached to it.

When I want to get the full monty on the rare occasion, I go to a nearby multiplex....pre covid that is, though it isn't something I greatly miss.

There is one thing to try though. True play is the Sonos opinion on good sound and may not always be what all agree with. So, toggle it off in the controller to see if that changes things for the better in your case.

If it does, leave it off.

Thanks I’ve tried with that toggled both off and on and the tv speaker still gives it a run for its money. I didn’t think an internal tv speaker would be even close to a Sonos soundbar but it is. So think should have really gone for arc in hindsight if it is much superior. The sub sounds an attractive addition but at nearly twice the price not sure if worth it at this stage.

Ask Sonos/retailer if the absence of the packing box is really a hurdle if you wanted to return beam for an arc.