No. The limit is a soundbar, two rears and two SUB’s It would be possible to use an AMP and 3rd party speakers rather than SONOS speakers for the surrounds.

I’m sorry I should have clarified…that is my current configuration. I have an amp and third party rears right now.  What I’m asking is if I could add 2-Era 300’s to this configuration and if so where should I place them.

I own currently in my setup:

-Arc

-sub Gen 3

-AMP powering rear channels

add Era 300’s?? Thanks.

You can add ERA 300’s as a separate Room and Group them with ARC. When playing TV audio through the ARC, there will be a time skew with any Grouped Room.

To some extent you can adjust this skew with with TV Dialog Sync, but at the potential cost of some lip sync.

What about for Atmos content on Netflix Apple movies, etc.

Also where should they be placed within my current configuration?

You can only add two surround speakers to a Sonos home theater setup. So if you added the Era 300s as surrounds, the Amp/in-wall speakers could no longer be included in your Arc setup. You have to choose one or the other.

You could group the Amp with the Arc setup when streaming music though. But when playing TV audio, you will experience an audio delay from the Amp/in-wall speakers.

So it’s not possible to have a 7.1.4 with Arc and Era’s being dedicated Atmos speaker?

An Arc + Sub + Era 300s setup IS a 7.1.4 Dolby Atmos setup.