Home Theatre setup question

Yes, but initially add each of the Era 300s to separate rooms, do not stereo pair. Don’t worry about the given room names for them.

You can then go into the room settings for the Arc Ultra and select Add Surrounds and follow the process.

“Room” is just a label.  You can name them ‘Fred’ or ‘Barney’ if you wish.  Best thing is to name the soundbar the actual name you want the room to have (‘Living Room’, ‘Movie Room’, etc.).  Then name the surrounds and Sub anything you wish (For my living room, I use “L LR Surround, R LR Surround, LR Sub).  The name really doesn’t matter, they will be incorporated into the soundbar in the end.  I just name them like that so if I do remove them from the room, I know which is which.   Do not stereo pair the surrounds.  Then follow these instructions to add the surrounds/Sub to the soundbar to make one room.

https://support.sonos.com/en-us/article/add-surround-speakers-to-a-sonos-home-theater

https://support.sonos.com/en-us/article/set-up-your-sonos-sub

If you want a home theater Room the above advice is what you want.

You  could set the Arc and each 300 up as a different Room and put each in a different room of your house. You could then seamlessly stream music on any/all when set up like that but the TV sound would see a slight delay going to the 300s.

The Sub can't be a Room, it has to be added to an existing Room.

The different setup possibilities can be confusing!

Ty guys