What is this wire from battery to AMP? There are 2 AMPS in my 94 E500 and both were replaced at a local stereo shop with "used" (more like defective) a few years ago. I never saw their work until today and don't think this is stock wiring. I want to put everything back and can only assume this hot fused lead was put in by the installer who sold me the used amps. Perhaps the used amp he sold me did not work properly and therefore he had to wire a hot lead? I thought it was a switched signal from the head unit? I have a 1492 Becker head unit and 2 amps that are Becker units 124 820 17 89. The idea of a hot lead all the time to the AMP does not sit with me. I have searched the electrical section and wiring diagrams but they lack the pin out detail of the amps. I disconnected the lead from the battery and put a wire tie on the end. No sound anymore now. Notice the in line fuse. Is this a bad amp that the installer just worked around? Maybe the relay within that switches power is bad?