I got an Xitel MD-Port AN1 off eBay earlier last week and put it in today, Sounds great .
I was worried that maybe the signal would be weaker then the signal from my sound card but matches up without having to use the source loudness on the headunit (actually i turned it down a little 2dBl). On my home PC with Sonique i noticed a skipping in the middle of the song and then a big jump in CPU usage but in the car with winamp it plays fine.

There is somemore of em on ebay, but a little but more then i payed.

Pic on the Webpage