It can ‘t be paired (be put in the same “room” in the Sonos app), but you could group (having two “rooms” play the same music) it with the Roams. Since the Roams do not do spatial audio, you’d lose that function on the Era 300 when grouping.

https://support.sonos.com/en-us/article/group-and-ungroup-rooms

If you just want to use your system for music, I’d listen to the Five too.

So to be 100% clear I would lose the spatial audio effect of the Era 300 just because it would be “ grouped roomed “ ? ? Thus reducing the Era 300 to what ?  Just a 1 dimensional speaker output with the stereo roams ? Wow ! What a propriety limited system if true. 
 

Garrett 

The Sonos Roam cannot play spatial audio, so the stream to all would be stereo only, otherwise there would be a need for separate streams, that likely would risk ‘sync’ issues, so it’s best for all to play just the one stream. The limitation is the paired Roams in this instance. If you were to group (up-to 32) rooms that were all capable of spatial audio such as Era-300’s, Arc and/or Beam (gen2), then ALL would play the streaming Atmos audio. 

Thanks Ken for your reply, my mistake was to conflate “spatial audio “ with “ surround sound “ , thus would the Era 300 still output its full surround sound when “ group roomed “ with the stereo paired Roams ? 
 

And aesthetically what would it add to the existing set up sound experience ? 
 

Thanks, 

‘Garrett 

As Ken stated, the source for grouped rooms will be downgraded to the lowest capabilities of the group.  So a 300 grouped with a Roam will not play spatial audio, it will play stereo.

One must know the terms to understand what's going on here.  A stereo pair is a concept in audio, it has a defined setup, and it has placement requirements to create a stereo sound stage.  The same goes for two Atmos or spatial audio speakers, or a 5.1 or Atmos theatre setup.  This is why Sonos "bonds" these configurations together as a semi-permanent cohesive room which is able to play the sources (stereo, 5.1, Atmos audio, Atmos theater) they are created for.

A group has no cohesive configuration.  It's an on the fly grouping of two rooms to play the same audio.  There is no assumed placement (they could be in the same location, or opposite sides of the house).  The only technical requirement of a group is they need to play the same stream.  So if one room in the group is limited to stereo, they all play stereo.

Best advice?  Follow Sonos' cue and setup each room as a bonded room of like speakers.  Don't try to mix and match in the same room by grouping.  It doesn't always sound better just because more speakers are playing, and often it sounds much worse.

Do the Era’s do surround sound without a Sonos soundbar?

The 300s do Atmos audio from Amazon Music or Apple Music without a soundbar.

I think you’re asking, if you play stereo music audio to a pair of Roams and then group them with a Sonos Soundbar HT, will the Era’s surrounds bonded to that Soundbar play the stereo music too?… The answer to that is, if you set the Soundbar to ‘Full’ audio output for music rather than ‘Ambient’, then ‘Yes’ the Era’s will output the stereo audio, which is balanced with the stereo audio output from the Soundbar. You can of course set the audio to ‘Ambient’ to ‘compliment’ the Soundbar stereo audio output instead, or there are options in the Soundbars ‘surround audio’ settings in the App to disable the Era surrounds too.

On my Lounge Arc/Surrounds/Sub - I have them set to ‘Full’

On my Bedroom Beam/Surrounds/Sub-Mini The Wife and I have them set to ‘Ambient’ as the surrounds are on the bedside tables/cabinets and the speakers are close-by when in bed. So that’s our preference.

Hope that answers your question?

Thanks Ken and others for all your comments, I think my question got a little side tracked due to my initial misuse of terms. Sorry about that. 
 

Just to bottom line my question if I may , if my 2 Roams  are combined with only  1 Era 300, in the same room, will the Era still put out its full surround sound ?  
 

Thanks 

Garrett  

There’s the Sonos lingo again. This depends on what you mean by “if my 2 Roams  are combined with only  1 Era 300, in the same room”. This phrase contains two words that could be seen in different ways.

To start with the word “room”. Would this be a room in a physical sense or a “room” in the Sonos app? Because if you would try to put the Roams and the Era in the same “room” in the Sonos app you would find you could not - a Sonos “room” is a defined set of (stereo or surround) speakers and two Roams and an Era cannot form a stereo or surround set so can’t be put in a “room”. To use your phrasing: they cannot be “combined” in a “room”.

Since you have to use two “rooms” in Sonos (one for the Roams and one for the Era) you can “group” both rooms, see my link above. In this way they can be “combined”.

Now to answer your question in the correct lingo: when grouped with other rooms consisting of Sonos speakers that are not Atmos capable, the Era will not play surround and pick a non-surround stream.

Thanks 106rallye, sorry to be dense , I am not new to sound reproduction , professional musician working with both live and studio sound amplification for many years buuuut am new to the Sonos referential terms, but I think I got it finally ; Atmos IS surround sound , and surround sound IS Atmos , right ? My bad, I somehow thought Era 300 played any audio feed as surround sound regardless of whether it was Atmos or not. 
 

‘Garrett 

So I understand the room concept and sterio pairing to the lowest capable one . I got a Sonos Roam in addition to Sonos Era 300, but they just wont pair even in stereo mode. It says no compatible device. What am I doing wrong?

You can only stereo pair ‘like’ devices that are acoustically the same, as examples, an Era 300 with another Era 300, or a Sonos One with a One SL, or a 2x Roams, or a Roam with a Roam SL etc. If the two speakers are different, then the next best thing is to just group them. See this link:

https://support.sonos.com/en-us/article/group-and-ungroup-rooms