Yes, but the line in on every speaker will be subject to the 75ms delay, as normal with all line ins. Essentially, you’d set each Era 300 up as its own separate ‘room’ in the Sonos software, and adjust the relative volumes. At that point, you’d probably never want to touch the Sonos controller again, lest the volumes get messed up.
If you’re trying to use this as a video sound system, the delay will be too much, and there is no way to feed a separate signal just to a subwoofer.
Do you have to disable wifi somehow.. when I try this it picks one input signal and fires it to all Sonos speakers
You should see multiple line-ins as input source options. Each Era needs to be playing its own line in source. Don’t group them, as this will have all of them playing the same single source.
This has so many potential problems that it begs for an answer to the question: why?
The community could probably talk you through some alternatives.