2000 mercedes E430 stereo

that vehicle has a fiber optics audio system along with some other things tied into it, use a line output converter after the factory amp. To make things worse some of those cars have a microphone that monitors the sound and will adjust it if it hears to much bass or to much highs, you may have to disconnect the mic to or it will sound like crap when you add the subs, those cars suck to mess with!!

Jazzy