Pairing multiple Connect:Amp

Yes, as in group them together. But the grouping will not survive mains power cycling and will have be done again.

But not as stereo pairs, correct?

You couldn't stereo-pair two CONNECT:AMPs. That would imply that a single unit could run the amps in bridged mono, which is not possible.

Ah, I hadn't made that logical connection, although I knew that part. Silly me. Thanks, ratty. Too early in the morning for me, need more caffeine.

There are really lots of ways to get this done, and the best solution really depends on what exactly you want to do.
For example, if you want this all to be one zone, then it might be best to get a CONNECT and then an AMP (non-sonos) to power all 8 speakers. If you are ok with 2 separate zones (play the same music or different), then get two CONNECT:AMPs, as you could power 4 speakers off each. If you need 4 different zones, then get 4 CONNECT:AMPs.

FYI, I don't believe it's recommended, but I have run 6 speakers off of one CONNECT:AMP and a speaker switch before without issue.

If you are ok with 2 separate zones (play the same music or different), then get two CONNECT:AMPs, as you could power 4 speakers off each.
Only if the speakers are 8 ohms each. CONNECT:AMP can take a combined load of 4 ohms.

Can we pair 2 Connect Amps , one to run two front speakers in a stereo and the second to power the 2 rear speakers as surround. I have 4 ceiling mount speakers 2 in the front and 2 in the rear.

Also as a follow up , if the above is possible , can we add a 3rd party sub to one of the 2 connect amps to complete a 5.1 setup ?

No. You can set up a CONNECT:AMP as a surround speaker with a PLAYBAR, as noted here:

Setting up CONNECT:AMP as surround speakers

However, without a PLAYBAR or PLAYBASE, there's no way to get a 5.1 signal in to and interpreted by Sonos.

Bruce, Thanks for your response. This kind of sucks. The only workaround would be basically to either run front and rear channels in parallel (assuming both of my speakers are 8 ohm) which will basically have same level of sound from all speakers or alternately use a Connect product and a 5.1 receiver (that I already have) to run a true 5.1 environment. Do you know if this is the hardware limitation with Connect Amp or a software update that Sonos engineers can help provide?

Any Sonos engineering members in the community that can comment ????

Heh. There's tons of issues here. Nothing but a PLAYBAR or PLAYBASE has a chip in it that will interpret a 5.1 signal. That being said, there's absolutely nothing stopping you from getting a 5.1 output from an A/V receiver, and hooking up 2 (or 3? or 4? Never thought this through specifically) CONNECT:AMPs to a line level (not powered) output to feed a 5.1 signal through to the speakers. It's just a bit complex, and cumbersomely expensive. Plus, you have the added issue of lipsync, since any analog input to the Sonos system incurs at least a 70ms delay, and depending on settings, more, for processing.

It's not a simple software update, to be sure. I feel confident that there's no chip inside the CONNECT or CONNECT:AMP that can process a 5.1 signal.

Basically, Sonos made a product decision that if the customer wanted to deal with a 5.1 system, they'd need to purchase a Sonos product that would deal with it effectively, i.e. the optical low latency input, and the 5Ghz connection between the device and the surrounds and subs. All of the rest of the equipment uses 2.4ghz, for maximum range.

What you are trying to do here is "hack" a system to do what it wasn't designed to do. An admirable goal, but expensive, difficult, and unwise.