well i dont know if this will help, but if you plan on installing an aftermarket stereo in your audi, then there is a great possability that you shuoud repace your rear speakers, because they have built in amps, and with the aftermarket stereo, they tend to sound a little crappy. but to get back to the main point, there is no wiring harness adapter for an audi, but what i did was trace the wires back to the speakers, this was easy because the wirees coming out of the dash have pairs, which means the speaker wiresare twsted together or at least should be, they are not each the same color, ut once traced this is an easy process. I used insulated spade connectors and made my own wiring harness adapter to use is i every decide to change out the stereo. I hope this inspired you at least a little. sorry if i couldnt, but i am soon goingf to change my stereo and if needed i will write down my wiring diagram i made and let you know what colors are what.