“Are you sure each wireless subwoofer kit (RF-WSW312) is "uniquely paired" with sender/reciever? I have one already in living room upstairs and need another one in the basement. BUT am concerned there will be interference if both pairs are ON at the same time (i.e. both system working at the same time). Let me know if these units are uniquely paired in terms of frequency so I can either buy the same brand or look for another brand online. THanks.”