The Arc is a soundbar, not a center channel speaker, and thus already has the the left and right front speakers built in.  There is no way to turn those speakers off and have the room use different left/right front speakers instead. You can bond an amp to the Arc for rear speaker duty, but not for additional front speakers.

As for the sub it cannot be used for two different Sonos rooms at the same time. So no, it can’t be bonded to your Amp and your Arc at the same time.  Of course, you can reconfigure the sub to be in one Sonos room or the other as needed, but that requires some time to do, and will remove any trueplay tuning you may have done.

This sort of functionality is something we’ve seen requested on the forums before, but Sonos has shown no indication to do this sort of thing.  I personally don’t think they ever will, since it would make more sense to make a center channel speaker for this use case, rather expect users to buy a full soundbar and not use the left and right channels on the bar itself.

I don’t get why it would not make sense.. wanting to use a sub with multiple setups seems quite a normal request. Since the Arc is not ment for playing music imho… and the Sub with good speakers is. So basically you cannot have both a home cinema setup and listen to music on a good system in one room unless you invest in 2 subs. Doesn’t sound logical to me.. Same for music on the tv. The Arc+speakers is better then a soundbar...

I did just figure out I can just group the two together as two seperate rooms can be grouped. This works as well, despite being a bit clunky..