Chony
Perhaps the best for you is to use the SUB OUT in the Tyros mix.You says it does not mute the MAINs,Yes itis.Imput a jack on your Sub only a jack no cable with it.Switch the part you want (rhytm 2) in your case on the sub who your jack is.If you want stereo use sub 1 and 2 and switch part on SUB1&2