I have a 97 Mustang that was equipped with a basic factory system. I have installed several different HU's and just recently blew the stock speakers. First I installed Sony XS-R5743 all around. I was getting a bad crackle from all of the speakers at mid range vol. I took those out and installed Kicker KS-680's all around, I was getting the crackle at about the same vol. with the sony's. I installed a different HU, I can get a little higher in vol., but I am still getting the crackle. What do I need to look at or install or look for? any help would be greatly appreciated. Both recent HU were Pioneer.