Multiple Subs

Generally, placed correctly, two subs reduces the nulls and peaks.

Sounds awesome I’ve just bought sound bar sub and to play fives for surrounds plus I’ve got 4 play ones and 2 play fives mk 1s and to play fives mk2 I love them all brilliant bits of kit

No. Actually, there are disadvantages due to the large wavelengths interacting and causing null areas or "standing waves".

Wrong. Multiple subs smooths bass and reduce peaks and nulls.

Sounds awesome I’ve just bought sound bar sub and to play fives for surrounds plus I’ve got 4 play ones and 2 play fives mk 1s and to play fives mk2 I love them all brilliant bits of kit

Why would you use play 5s as rears? Seems like a giant waste of money. I don’t think you would notice a difference between play ones/Sonos ones over 5s as a rear channel. Volume is minimal and most bass is channeled through the sub. I wish Sonos would allow for a second sub to be used and tuned in the same zone.

I love having my Play 5s as rears for my Playbar, most specifically when I use them to play music. I have it set for "Full" for music playback and I get an amazing stereo pair that fills my room. I also have a second "room" off to the side with another subwoofer and a pair of Play 1s. When I'm playing the whole house during parties, I actually bring on three subs, 4 Play Ones, along with a Play 3 for coverage. There's not a dead area in the house and when somebody wants to turn it up, there's plenty of bass to go around no matter where we're at.

That being said, I would have like to be able to simply add multiple subs into one "room" without faking a three room "group" and simply turning off the "extra" Play Ones. It's flexible but not perfect. I haven't had a single complaint at any of our house parties.

Someone mistakingly posted above that multiple subs causes standng waves. Uh, no. Multiple subs can acutally help with standing waves and creates more uniform room coverage. The more subs the merrier.

That being said, was hoping to add a Sonos SUB to an existing Sonos theater system (PLAYBAR + SUB + PLAY:1 x2), but sounds like it is not possible? Think I understand the workaround posted of combining two Sonos zones with subs into one room but don't technically see how that would work in a Sonos theater setting. Would want Trueplay to tune both subs together as well.

No, it's not possible with Sonos software, nor would it be effective with two rooms grouped, as the room with the second sub would be at least 70ms behind the TV room.

You could certainly use the "two room" work around with music streaming, but not with a TV (digital) input.

If (and you can't) you could add two subs to one room wouldn't TruePlay just dial the volume down on both of them to keep the sound levels flat?

I've seen that volume reduction with two non-Sonos subs and active equalization.

No. Actually, there are disadvantages due to the large wavelengths interacting and causing null areas or "standing waves".

I suggest you do some research before you write all that nonesence. Multiple subwoofers, actually correct the very same wavelengths issues that one sub causes in a residential environment, specially for multiple seating positions. 

Extensive research has been done on the subject.