I'm trying to add an AUX in/MP3 connector to my Symphony I system. I've got the pin connector diagrams, and it looks like it should be fairly simple to connect the left and right channels of the CD Changer input to a cable. The problem is, how do I trick the HU into thinking there is a CD changer connected, so that I can select these inputs? (there is no CD changer currently in the car). I've seen some devices on eBay and the like for £30-50, but would rather not buy one of these as it looks like it should be relatively simple (you can correct me on this).