I don’t think the MAG6R model is the same as the “Sonos Architectural by Sonance” in-ceiling speakers, so you will only be able to connect four of those speakers to the Amp.

If you want to connect six speakers to the Amp, get these speakers: https://www.sonos.com/en-us/shop/ceiling-speaker-pair.html

Here are the Sonos Architectural by Sonance in-ceiling speakers at Best Buy:

https://www.bestbuy.com/site/sonos-architectural-6-1-2-passive-2-way-in-ceiling-speakers-pair-white/6325620.p?skuId=6325620

Odd that they’re listed as Sonos. They’re actually Sonance speakers. Sonos is just a reseller. 

Probably because they are branded as Sonos speakers in name and on the actual speaker.

Most odd.

And, I believe the impedance of the “Sonance” speakers is equal to the private label “Sonos” speakers. This means I should be able to connect six (6) speakers to one amp. The only issue is the Sonos branded speakers have True Play while the Sonance do NOT. I really wish I could get a real answer from someone @Sonos. 

@seattlesounds From the Sonos Amp FAQ:

Will a single Amp power more than two passive speakers?

Amp can power two pairs of 8 Ohm nominal passive speakers when wired in parallel. Amp can power three pairs of Sonos Architectural by Sonance wired in parallel.

You can only connect four (4) of the Sonance (MAG6R) speakers to the Amp.

If you want to connect six (6) in-ceiling speakers, they must be the Sonos Architectural by Sonance (INCLGWW1) speakers.

No, it does not.  The Sonos labeled speakers are specifically designed to work with the amp to enable connecting 3 pair.  I don’t know how exactly this is accomplished, but it most certainly does not mean any speakers with the same impendence as the Sonos lableled Sonoance speakers can be used in 3 pairs to 1 amp.

You asked the community forum and got an answer from users.  If you want an answer from Sonos support, why not look there?

https://support.sonos.com/s/article/4759?language=en_US