I have a set of Klipsch Pro Media 5.1 speakers. They have worked very well for the last few years and really never abused except a few times. These speakers for whatever reason seemed to have a lot of complaints about blown subs but I really think its because of the people using them. I know Best Buy had them and they were expensive and then they dropped the price to some ridiculous amount to clear them out. A blown sub is not problem..
Anyhow I'm getting a crackling sound occasionally. I think I tracked it down to this: http://forums.klipsch.com/forums/t/96150.aspx
I've taken the back panel off the sub and powered it up. You can actually here the crackling coming right from that chip or very close to it. The crackling is transferred to the output of the speakers, raising or lowering the volume doesn't raise or lower the crackling/buzz It comes and it goes but it seems the electricity has something to do with it too. For example if I power them on this crackling/buzzing is pretty loud and then it fades out. I have an air conditioner near by and if it powers off to fan mode they'll start crackling then it will fade away. It did this before air conditioner was there so its not the cause of it.
I've heard of line conditioners before and I'm wondering if that might help.
I can send them to get it fixed but its like $60 +S&H, plus its a 4 to 6 week wait. At least that is what they said.