I resently picked up a new system to replace my old junk.I'm running an Onkyo TX-SR601 with Polk RM6700 and a Polk PSW202. I'm having a problem with the sub. I have a loud pop when things get exciting in a movie.The funny thing is that I noticed it's ONLY with Disney THX movies. It's easy to turn it down to get rid of the problem, But I don't want to. Is this a problem that can be fixed or should I consider a sub upgrade.