Not sure I truly understand the question properly.

In a 5.1 system, there are 3 channels which are part of your Arc. You can then add 2 surrounds to that (of the same type,) so either your two Sonos Ones/ PLAY:1s, or your two Symfonisk lamp speakers….but not both. Then you’d add the subwoofer, which would be the .1, and you’d have a 5.1 system, with two speakers left over that you could set up for music use in another ‘room’. 

Ah gotcha, thanks for the reply! I understand now. I was under the impression you needed 4 speakers. I'll just sell my play ones as I've had them for several years. I was still thinking of a traditional 5.1 setup, like two front speakers, 2 rear, Sub, bar and receiver.

You can’t do two ‘front’ speakers in a Sonos setup, those channels/speakers are already in the Arc, but I completely understand. Sonos doesn’t make any ‘center speaker’, they all include those three channels. 
 

You should get a pretty good price, I’d expect, on the PLAY:1s, I think there may be lots of folks who need ‘just one more to fill out my surround needs’…

In my previous house I had the two Play 1's in the rear with the Arc and didn't think anything of it lol. Guess I should do more research before I buy things, cause I've had the 2 Plays sitting in the front with the Arc lol. I'm an idiot. I've had the Arc since it was released. Thanks again for the help

Navin 

You can never have too many Sonos!

Don’t you have a bathroom, garage, basement or something that could use a Play 1 or two?

Most welcome, and not an idiot, just had a slightly different world view ;)

 No basements in Florida as far as I know and I got a small 1700sq 3 bedroom house, so just turning it up in the living room let's me hear it in the entire house and in the garage I have the Move

Navin