Music will play to grouped rooms in sync. Just set up Room1 and Room2 each as a stereo pair. You can then create a named group, or just group/ungroup them as and when it suits you. Choose your room, start streaming music to that room, then group in the other room. Or select the grouped rooms and start streaming to the group. Whichever way, music will be sync’d.

Nik, thank you for the confirmation.  I wasn't overly concerned it would be an issue but just wanted input from you guys with more complex systems than mine is right now. 

ETA

The existing pair I routinely use the touch controls rather than going to the app once the room is active.  Once the 4 are grouped will the touch controls on one pair control the volume on the second pair as well. Ultimately both pairs will be at the same volume. 

I think the buttons will only control the pair, not the group. 

I thought that was a stretch but was hoping lol. That would be a nice firmware tweek.

Thanks again nik. 

No problem.
 

Perhaps a moderator will be along soon, to add this as a feature request? Who knows if/when it’ll be implemented though. 

Generally, stereo pairs are in separate physical areas and you would want to adjust Volumes separately when touching a speaker. I suppose an option could be added, but this is not so simple because Grouped speakers might sometimes be in the same physical area, but other times not. In general SONOS is reluctant to add more and more options because this risks becoming “complicated”. 

buzz the scenarios you describe are viable issues, I agree. Maybe my situation is much less complex than most,  a large rectangular room that will have speakers in each corner hence all levels relitive to each other would be the same. I, at this time watching the struggle with the app, wouldn't advocate for change but a simple switch to allow coupling the controls within a room with multiple speakers seems well this side of complex.

Using the app, the default volume slider controls the group. Separate room controls are also available. 

Sonos has a relatively new feature, zones, that might be a better fit for your situation.  It does have some limitations, as you can’t create stereo pairs within the zone, you can’t tune, etc, but this may not be too concerning for your situation and room layout   You can have all 4 speakers act as a single room, always playing the same audio at the same volume (I think you can set relative volume between speakers).  I am pretty confident that controlling volume via hard buttons on the speaker would control the volume for all 4 speakers with this setup.

Anyway, if you are going to use 4 identical speakers in the same space like your rec room, you have the option to try out this configuration and see if it works for you.  If not, you can always go with 2 separate Sonos rooms plan. 

Seems like something to play with but it's a bit disheartening that you can't have stereo pairs in the zone.

This rectangular room has a pool table dead center.  My original idea with the 2 stereo pairs was to set them positioned in each corner set so they all center on the middle of the pool table. I THINK that after setting up the second stereo pair would be too swap the L/R channels one one set so basically the speakers along each long wall would be the same channel. I can fill the room now with good sound now but the end with the speakers can get a little loud when someone says "good tune,  turn that up". 

Normally, when people are around I have the living room and a set of 100s on the covered patio playing the same stream. I'm thinking the volume control of the rec room can be dealt with the master slider in the app, zeroing the 2 pairs then using the master, only dealing then to drop the other 2 areas to not blowup people there. 

Not ideal but workable.

I think the ‘Zones’ feature was a ‘pro’ feature, designed for restaurants and similar installs that was easily ported to the public side of the system, and made available to us unwashed masses. It seems ideal for lots of ‘rooms’ that are single point speakers. Not necessarily ideal for every system, but it is functional for the intended use. For those of us who use stereo setups, there are other methods, as you suggest. 

The issue with two sets of stereo speakers in a room is which to set as “left” and which as “right”. Because folk can move around, they could find themselves hearing the two “left” channels rather than a left and right. I suspect that’s why zones (a Pro feature) only supports mono speaker configs.

I’m not sure how Five or Era 300 would fare, as a single speaker can play stereo sound?)

So few perfect sound stages.…

Sorry, couldn't pass it up. Ah the good old days. 

FWIW, I have a large rectangular room with multiple speakers, and have found that with guests, the stereo setting is not ideal.  We find it much better to group the four rooms in mono.  The sound coverage for a large space is much more immersive, since people are rarely in the stereo sweet spot anyway.

To add, it gets really weird with older stereo mixes, such as the Beatles, when all of the vocals come out of the left speakers, and the instruments come from the right.  Just doesn’t work if you are hearing only half the track in an entertaining situation.

The Era 100 also plays stereo as a single speaker.   From the ‘Zone Guide’ it does mention that the Era 300 plays stereo, but nothing on Sonos Five or Era 100.  I suspect the note is to show that you can’t play atmos music with the Era 300 when in ‘zone mode’, but it’s not really clear.