When I first got my PL-200, I didn't tell my wife. She was gone the day I received it, so I hooked it up and put it in the same place as the old one. I forget which movie we watched that night, but one of the first bass rich scenes had this violent forward/back effect. My wife looked over with this puzzled look on her face and asked "What the heck was that?" I had the level on the sub way too high, and it felt like it actually moved the couch.