What is the best way to interface with a factory head unit in a VW GLI
I own a VW GLI with the Fender Audio system. I love the head unit as it has all of the musical options I could ever use and I think they sound clean. Options include SD card, cd changer, sat radio, ipod interface and ipod/iphone music streaming. The high frequencies sound good as well. Fender made sure they got guitar sound right. After that though the system falls apart. Midbass and bass all sound like crap. Midrange is mediocre They (VW) installed some after thought sound deadening material on the back shelf underneath their built in sub but it did nothing to stop the annoying buzzing the bass is the worst quality I have ever experienced. I've got two old school amps a sound stream and an xtant both of which sound great. I then have to figure out if I can replace the speakers in the doors with some speakers that I have from an older system Morel elates or if I need to buy new speakers. lastly I need to figure out the sub probably a JL audio stealth box as showing the system is not a priority for me but sound quality is. I like my systems to be stealth in general. I'm not sure what the best products are for coming off of the head unit as I have always replaced them in the past. Thanks.