Hi GmanHB, the rear speakers need to be wired to the wireless sending unit included in the HW-Q850 box (typically placed behind a couch, etc.), so if the wiring and mounts allow it, they can replace the speakers mounted on your ceiling. The sound bar has left and right channels, so you can play either the sound bar, or your existing system, not both at the same time which would make your existing left and right channels redundant. Thanks! ^Scott