there was a write up a lil while ago by slow3z about hooking up a mp3 player into the stock headunit. i soldered the 2 wires together like it had said, with the 12v power supply to the red wire. theres one problem though, i can hear the music but its really faint and i have to have the mp3 player and stock headunit turned all the way up just to hear it. any1 thats done it know what could be problem? thanks