Aside from not having the ability to accept a line-in connection, something not possible due to the network configuration needed to act as surrounds what are you missing?
Hi @kevpun
What @Stanley_4 mentioned regarding the Line-in and Bluetooth being disabled is true. The main reason is that any Sonos speaker is no longer autonomous when used in surround mode. They receive all instructional behavior from the Sonos soundbar to which they are bonded.
The other “snippets” that you are most likely referring to are that the center speaker is disabled when used as a surround for Dolby Atmos content. That was a very big topic when the Era 300 was first introduced as many initial buyers felt they had a defective speaker or worse they had been “duped” by Sonos.
Rather than try to explain the reasoning as to why the center speaker is disabled when used as a surround with Dolby Atmos content click the link for an explanation. It is a live streamed event on the Era 300 hosted by Sonos engineers that explains the design and acoustics of how the Era will present itself in certain use scenarios. Hopefully, your questions will be answered and you can rest assured that you have made a wise investment.
https://www.sonos.com/en-us/sonos-live *
* This is a landing page. You must scroll to the Era 300 event and select it.