I have a 10" Klipsch KSW-10 HT sub. At louder volumes and deeper notes I get this sort of "bottoming out" distorted sound. Gain is turned up about 75%, Bass on receiver is at 0. I also found out in the past when I had it in my living room with roommates the one liked to listen to music pretty loud while it was distorting like crazy. (Don't get me started) You guys think it is just the amp clipping or the sub is shot? I really don't want to replace the whole unit if necessary.