I just picked it up. Car has a pioneer x4600bt HU. When I reach a certain volume, the speakers would go and off, clack long, popping noise. Previous owner has the unit professionally installed. He said they were never able to figure out why it does that. I need help! I would have to turn the fader to the rears because they work fine. Car has bose system. Everything else is stock.

 

I would take it somewhere and have them look at it for an estimate. Then hope they would tell you what wrong for a free of charge and then maybe you cna fix it yourself? Sounds maybe like a fuse or a shortage in the wiring is my guess.