If you unlink the Play:5s then you will have 3 separate speakers playing back in Stereo so the first question you should probably ask is how important is the Stereo image to you?

Of course adding the Era 300 the way that you have will already have created a “confused” Stereo image because the left channel of the Era will be aligned to the right hand Play:5. I guess you could harmonise this by physically swapping the Play:5s which would effectively realign things but would reverse the Stereo image. Of course this would still not give you a true Stereo mix.

If Stereo does not matter to you, and your aim is to fill the room with sound, then separating the Play:5s might work as you could then balance the 3 separate speakers to meet your taste.

To obvious question though is why did you not relocate the Play:5s to see if you could improve the sound in the room that way. Physical placement of speakers is a powerful and underused way to resolve a lot of issues. It is also relatively cheap (assuming that you have power sockets where you need them).

No.

No. Trueplay would tune the 3 different Sonos rooms as if they were separate rooms, not 3 speakers in the same room.

Maybe.  It’s hard to say without knowing more detail about the specific room.  As the poster above stated, in most cases you want the room to have a ‘sound stage’ where the audio is coming from one specific side of the room, focused on the primary seating area.  There are cases though where there isn’t a primary area.  And you want more mono audio, or a stereo that’s coming from multiple sources rather than a stage. 

Anyway, if I wasn’t happy with the pair of 5s filling the room, I would probably have opted to add a pair of 100s to the back of the room rather than a single speaker.

@ArthurHua would you describe the music you listen to as bass heavy?

If so adding a sub might be what you need as this would allow the Play:5s to focus their power on the miss and highs. 

You’ve already gotten excellent advice. However, I own Fives and Era 300’s. I’ve also played around with Fives and Era 300’s together in the same room just to get an idea of how they are tuned one vs the other. To my ear the Era 300’s for stereo are slightly brighter than the Fives. However, the Five produce more low end. That said if I were to consider placing 3 speakers in the same area and already had Fives I’d go with another Five to keep the tonal quality consistent.

If taking that route I separate each Five as it’s own room so as not to hear a stereo separation wherein an instrument may cross from one side to the other thus throwing the listener off relative to their position in the room.

Another stereo pair would work best then balance could be attained using the volume of each stereo pair.  Budget would be a factor in your choice of speakers, but you already have a 300 so save up for another 300.

 I like the 300s because the speakers fire in different directions filling the room which is what it seems you are trying to accomplish.

 They kick butt with Atmos.

Thank you all for your answers, really helpful! Attaching here a drawing of the room that I am referring to if that helps (the ERA 300 is placed ~8 feet high above the cabinets and the FIVEs are on stands).

I understand that I cannot add a 3rd speaker to a stereo pair (thank you for the clarification @melvimbe ) and that then my options are the following:

1. Go for mono sound and have each speaker be mono (getting rid of the stereo pairing) - I may try this as I am not sure I value that much the stereo image (although I need to try first)
2. Set up a second stereo pair where my ERA 300 is as @MoPac suggests, which could either be achieved by buying a second ERA 300, or 2 FIVEs or 2 ERA 100. If I do this, would it create a “confused stereo” though as @Gaham seemed to be suggesting?

@Gaham , I listen to a wide variety of music, ranging from jazz, to rock, to electro, to opera…

Really appreciate the help of this community - as you can tell, I am no expert here and your advice helps me a ton!

Thanks

Arthur

@ArthurHua A good answer can be given based on your answers to:

1. Whereabouts in the space are the most commonly occupied listening areas?
2. Is there a listening area most commonly used when listening to music in just one part of the space?

My experience is that in a very short time, the brain can compensate to make the music sound fine - as long as it does not stutter and stop often - the latter is something you can never get used to. Some differences in sound signature of speakers also get accommodated.

In my specific instance, most of my solitary listening is done where your sofa is, with three speakers placed behind it on a ledge behind the sofa. The fourth is a Sonos Sub, off to one side. 

To address the need for the entire space, including the dining area, I have a Connect Amp driven pair of Dali speakers, close to the room corners on the ledge behind the sofa, that affords good stereo imaging across the room near the dining table. 

But since I found that when I sit on the sofa as I do when listening to jazz/blues alone, I needed a third speaker to fill in the hole in the stereo image coming from the rear - hence a play 1 unit planted on the same ledge, in between the two Dali speakers, grouped with the Connect Amp. All I had to do to get this to sound good was set the max volume level on the play 1 to 80% to equalise sound outputs for the same slider volume levels on Connect Amp and the Play 1, playing in grouped mode.

This now works just fine for both distance listening in the dining space and my solitary times on the sofa, with music from behind me.

Finally, this being no expert may even be a better way to be; all you need to know is if the music sounds good, knowing that as you get familiar with how it sounds, it will usually get to sound better so long as it is not as out of whack as it would sound from your 5 units as presently placed, when seated on the sofa!

PS: the kitchen island is best served by a single Sonos speaker aimed at the island; if it has to be placed high, it will sound better when aimed at where people are when working in the kitchen.

Your profile indicates that you have an ARC, probably in another area. If you have surrounds bonded to the ARC, temporarily unbond them, set them up as a stereo pair, and move them to the kitchen. Place them inline with the kitchen table, one on the kitchen counter, the other on a stand or stool.

Another arrangement would be placing speakers at either end of the kitchen counter. Due to their more compact size, ERA 100’s would be a good choice. This would give better coverage for the cook.

Overall this is a difficult space.

I have a similar space conceptually, where the central core of the apartment is left open plan for living/dining/kitchen, with an adjacent large patio. All I do not have is the 20 feet ceiling in one part of the space. It takes some trial and error, but given enough speaker units, capable of being grouped as needed, it can be quite simple to address. I have two armchairs where the sofa is, and one of those chairs is my happy place every late evening, with music coming from right behind me via the three speaker set up, sounding as good as I am used to having it sound. Once speaker placements were satisfactorily finalised, I ran lan cables to all via DIY wiring, just to eliminate that last stutter which can be annoying.