how would you input dvd audio into the stock head unit?

 

You would have to use an FM modulator and a changer that plays DVD audio and there are none out there yet. I am putting a Panasonic HU in that plays DVD-Audio and I have looked high and low and there are only 2 or 3 out there and others have a screen ie, Kenwood 915 and the new Pioneer. I didn't want visual just the surround sound audio DVD. Panasonic made this HU in 2000 and it flopped as the price was exorbitant {1999.00} and there were very few DVD audios available. As they become more available and popular then players will follow but by keeping the stock head unit you will have to use a modulator to hook up an aftermarket player/changer. Then from what I have read and heard you sacrifice sound quality. Good luck!!