You can only use the Sub or miniSub with one Sonos Room at a time.

You can switch it back and forth between Sonos Rooms but it is a bit complicated, more complicated if you use Trueplay.

Ok but can I configure the Era 100 in Stereo and leave them in the same room where there is the beam 2, the mini sub and the 300 in surround or do I have to insert them in a new room? Thanks. Andrea

You unbind the Era 100’s for the Beam. They wil form two extra “rooms” in the app that you can pair to form a stereo pair (one “room” in the app). Then you bind the Era 300’s as surrounds. You can bond the Sub mini to any of the two “rooms” in the app, but not to both at the same time. Two “room” in the app can exist in one physical room.

By the way. Why not use the Era 100’s as surrounds and the 300’s for music? Surrounds do not do very much and the 300’s are the better speakers.

Before you set up your Era300 for surround, I would try them as a stereo pair. Then you can hear how they sound without your Sub mini, then with your Sub mini.

I have Era300 myself (Ultra-Sub 4-Era300 as surround) and it is primarily with music that they really come to life.
I don't think you will gain much by upgrading to Era300 as surround even though they have upward speakers. In addition, the sound ONLY comes from the sides and top, the speaker in the front is deactivated when they are used as surround.

Ok thanks a lot 

But with atmos or spatial audio tracks is it better to set them as surround or stereo? If I set them as stereo, can the 2 speakers hear the dolby atmos or spatial audio tracks? Thanks. Andrea

You are confusing Surround mode with Independent mode.

In Surround Mode you have two sources, TV and Streaming.

TV mode gives you no Mode options, it plays what the TV sends out.

Streaming gives you the choice of Ambient Mode or Full Mode. Ambient adds a light portion of the stereo sound to the Surrounds. Full Mode clones the right and Left front channels to the Surrounds.

I have Era-100s connected to my TV setup and haven’t decided which Mode I prefer, it is easy enough to swap back and forth. I do know for groups I will switch to Full Mode as it allows me to have an more even sound level across the room. I kind of like it for background music for the same reason. Ambient or even Surrounds off gets some use here when listening to stuff where the positioning of the music sources is important.

I also have Era-300s as a Pair, they play what they are sent so stereo or Atmos, depending on the track they are streaming. Quite noticeable when an album has a mix of HD and Atmos tracks with the Atmos ones sounding much more room filling and I don’t notice any imaging issues.

Ok thanks a lot.

Andrea.

If I leave the 2 Era Minis as surround and configure the 2 Era 300s as Stereo, is the mini sub seen only by the Era 100s which are seen connected to Beam 2 or can I also have it seen by the Era 300s? Thanks. Andrea

You can only connect a Sub to one Sonos Room and it takes several steps to move it to another Sonos Room.

Ok at the moment I have the Eras set as surround. When I get the 2 Era 300s I'll set them up as Stereo to see how they go. But can I leave them in the same room or is it better if I tell them to put them in a new room? Then how do I select the Era 300s for example from an iPad or an iPhone? Thanks. Andrea.

They will have separate room names.  You switch between rooms by swiping up on the room box at the bottom of the app and tapping the room you wish to control.

Ok Thanks a lot.

Andrea.

Hi ​@Flyflot 

Here’s an example of having multiple Sonos ROOM’s in the same SPACE. I use the word space so as not to make things confusing when speaking of rooms. Here we go….

Space is 25 ft (length) x 18 ft (wide)

1. Arc Ultra with Era 300’s as surrounds and dual Sub 4’s_Room Name is “LG”
2. Sonos Five x 2 in stereo pair with Sub (Gen 3)_Room Name is “Five”
3. Sonos Amp with Turntable, Sub Mini and 3rd party wired speakers_Room Name is “Turntable”

All rooms are in the same space.  I just select which Sonos speakers I want to use by selecting the “room” in the Sonos app. I hope this clarifies things in case you were still scratching your head 

Ok Thanks.

Andrea

Sonos used to call Sonos Rooms - Zones, and this all was a lot less confusing.

Easy to explain having two different Zones in one room of the house.