Has this happenned to anyone else? Every time I think I have it adjusted right, I'll be watching a movie with a lot of gunfire, action (anything with a lot of bass), then all of a sudden the sub makes this loud popping noise. If I turn it off, then on again, it will go back to normal until the next action scene. I have an older Velodyne sub with it's own amp, and the receiver I'm using is a new (about one year old) Yamaha RxV550. The funny thing is, if I set the Yamaha for "all channel" and crank the sub as high as it can go, it will shake a lamp off the table and there is no breakup or popping at all. I think the sub is fine, maybe just a setting is off or something? Any suggestions? Thanks!