You can only bond the Sub with one Sonos room.

Your Playbar/surrounds/Sub is considered one Sonos room, your stereo Play:5s another Sonos room.

If you want to use it in another room, you have to use the app to move the Sub from one room to the other. That is the ‘switch’.

And that switch is quite cumbersome. The ability to use Sub with multiple rooms automatically is probably one of most requested features when it comes to Sonos. Particularly, since placement of Sub is less relevant than for other speakers so in theory the Sub could easily do double duty from the same spot in two rooms, e.g. in an open plan situation.

Sonos will point out that it is not a one second process to switch designation from the Sub from Room 1 to Room 2 anyway, so that users will complain that you can’t switch between set-ups just by changing source. One could argue that Sonos could also implement the ‘switch process’ by having a series of events triggered by e.g. one selection slider and that the user will just have to wait a little. I don’t know if that would cause issues with available memory though. Either way, I guess Sonos’ position will also be that you can also buy multiple subs to have a flawless process when starting Room 1 and/or Room 2 either sequentially or in parallel.

That’s awesome, thanks! Shame it isn’t a lot easier or more cost effective!