I bought the svs 20-39CS+ two weeks ago and I am very happy with it but I have noticed that as the volume goes up on my receiver the bass reduces itself(very noticable on music but also on movies), I can hear it but I can't feel it as I do when the volume is low. When I try the same material with my full range speakers as the volume goes up so does the bass and I can definately feel it as it moves everything around me including the couch. I have the 8200 Marantz receiver and all the speakers are set to small, the sub is powered by an Adcom 555-II. What I am trying to say is that I expect the low and high frequencies to increase or decrease evenly as the master volume goes up or down. Should I invert the polarity of the sub? The sub is located close to the left hand corner of my system behind the front left speaker. the sub has about six inches of breathing room around it and is about 2 inches away from the wall at the back.