I am having some major troubles. I installed a custom sound system into a C5 Corvette. The deck is a KVT-7012BT Kenwood ( I used speaker wire to ground the RCAs). The speakers are Pioneers; two front 6x9 and two rear 6½ with a dual self-amplified sub box. The speakers are run by FCAs through an Alpine KTP-445U head unit powerpack amp. The sub box works fine. The system sometimes will sound amazing. But after I get it sounding great I will turn off the car, come back the next time and it sounds miserable.
The sound is not an engine whine. It is associated with bass. The speakers muffle or crackle under bass at ALL volumes. So if I have the volume turned on high it is noticeable, if I have it mid it is VERY noticeable, and low it is still there in the background. It almost sounds like the speakers would if they were blown, but all four speakers have it and if I get it working right you can tell the speakers are in great shape.
The strangest part is I try to adjust the gain on the amp and after a few tweaks it sorts itself out, then when I get back in the car the next time it sounds awful again.
It also pops slightly, and randomly blows fuses.