I bought a 2005 300 Limited. I love the car it's a first for me. The only problem is that only my front three speakers work. The ones in the door and the rear do not. I've tried the fade and all of that but nothing does the trick. I think the factory amp has gone bad. I want to replace the amp with something else but not sure if I can. Can I buy just any speaker amp to make this work? Will I need any special adapters or anything like that? If anyone else out there has replaced the factory amp with something better I'd love to know what you did. Any suggestions would be great.