I recently purchased an ML soundbar for watching TV but still plan to use a Yamaha 5.1 amp/receiver for movies. Is it ok to connect the soundbar subwoofer output and the yamaha subwoofer output into the single subwoofer input using a y-cable? I don't plan to have the amp and soundbar in use at the same time, but if they were both on inadvertently would anything be damaged by having the sub signals combined?