hey just got a3 with concert head unit with 6 disc changer. i want to fit a pioneer 6700 which is no prob except for wiring the rear amp and sub. one yellow plug is all that needs wrining. one terminal for power and a common earth, no problem but the signal for the speakers, i think they need a low voltage signal, would high power signal cause damage, any ideas...

 

I'm not completley sure what your problem is, but i can suggest that all you really need to connect the new head unit to the OEM head unit is a wire harness which you can get from most car audio stores. Also, most newer head units come with a subwoofer out RCA connection so all you would need is a long enough rca cable to reach the amp as well as a remote wire that will signal the amp to turn on(that connetcion will be made from the head unit). Hope that helps. Dont forget to groung the amp as close to the amp as possible! Good Luck.

 

really all you have to do is look at the top of your factory head unit. There will be a wiring diagram, if you know what you are looking at you will be able to to find out which of the wires are left, right, and common. After that all you have to do is strip the wires and solder on RCAs, oh and the amp turn on wire is in the same harness. If you do everything right you will be good.