Originally Posted by onehundred80

I know little about this audio stuff but I think you are using the wrong adapter.
The pre-out RCA plugs should go directly to the amplifier and not into the wires that are in the OEM harness. If you want fader control front and back and left to right you need the RCA plugs.
The OEM amp is bridged left and right you need to separate them. Then get four RCA cables, cut off one ends plugs, open up the wire and separate the + and - wires and directly connect them to the amp. I did this and found you can get a kick in the kidneys from the woofers. Left to right and front to back faders work just fine.
That is my take on the situation, maybe I am wrong as I know little on the subject, but that is what I did and it worked.
You need theScosche adapter #VW01B or cut off the RCA cables on your adapter as there is not much room behind the radio.You also need four RCA cables, You have the aerial figured out. It is awkward attaching the eight wires to the amp and running them to the radio, I went directly there down the passenger side of the console and under the mat.


This is the wiring I used, it works as it should. No wires were used from the 'B' block of the plug or socket.