The Sonos Beam Gen 2 is a 5-channel soundbar. It outputs sound corresponding to the L, C, R, Ls, Rs channels. If you add rear speakers such as the One SL to the soundbar, it will change to a 7.1 system. If you pair the rear speakers, the rear speakers will be in charge of the Lrs, Rrs channels. The soundbar will be in charge of L, C, R. The question is then. Will the Ls, Rs channels still be routed to the soundbar? Or will they be routed to the rear speakers?