With respect to the surround Room, nothing can be added except an additional SUB. A pair of 300’s could replace the ONE SL’s in the surround system.

For music you could group the 300 with the surround setup. It would play louder but the stereo imaging would likely suffer.

I feel like the Ones are a good match for the Beam, the 300s seem to me to be more speaker than you really need as surrounds. I’m using Ones and Play 1s as surrounds with an Arc and a Beam and am quite happy with the sound in both rooms.

Thanks for replying.

probably better keeping what I have. And maybe upgrading the sink one with era 300.

I like my Play 5 in the kitchen, not as picky about placement or surroundings as a 300.

Mine sat on top of the cabinets in otherwise unused space.

My thinking behind was to add more to my system, without degrading the sound.

the way is set right now, the two one sl are next to the Tv the beam is behind the Tv, sonos roam, sort to the left side and the sub is behind the couch. So behind the couch is nothing that can emits any sound. That was the reason of putting the Sonos era 300. . My house has a very high ceiling and open space So to augment the sound , the Era will come into play? 
 If is not that any other recommendations have a complete all around sound.

The way to improve your sound could be to place the speakers the way they should be placed - if I understand your combination of speakers right, you’re after a surround set up, with the Roam as an extra?

If so the One SL’s should be placed behind you - in a surround set up that’s the way the audio mix is meant to be heard. They could be replaced by a pair of Era 300’s, but some think these are overkill with a Beam. By the way, the Beam should be in front of the TV, not behind - this is detrimental to the sound. If your TV’s is set low and the Beam would be I the way of the screen, set the TV higher up.

Remember there’s no separate front WiFi speakers in a Sonos set up and no way to ad more than two surround speakers. since the Beam already contains FL-center-FR, adding extra speakers is not deemed necessary Remember too that placing extra speakers in a separate “room” in the Sonos app and grouping them means the sound to the grouped speakers wil lag behind when watching TV.

Actually the roam was not bought as part of the system, it was more for travel usage, but did not like the power output, for the outdoor not that powerful, so is too late now to return it, so made it part of my system.

Will try the set up in a different way. Putting the Sl in the back.( just no outlet in the back to connect them.will find the way.