I found this whilst researching whether the 13 pin connector on the back of the stock radio in my 2000 Subaru Impreza Sport could be used as an aux input.
Looks like it can:
http://www.wakeworld.com/MB/Discus/m...tml?1096256753
I'm going to be giving this a go as I want to keep the hud and not have to use an amp.
Edit. Tried this, blew my radio up and had to buy another one. Moral:
1. Measure pin voltages before, not after you blow things up.
2. Connecting +13V directly to ground is a bad idea.
2. The pin out of the 13 pin connector on Clarion radios is
not the same across all the models with that socket. I've since found a second pin out that still doesn't match my radio.