I have the Bose Gold Series stereo with the CD player that displays "ERR" everytime I put in a CD. I talked to these guys today and said that was a common problem. I have subs and 2 amps sitting around but I am going to fix the Bose because it sounds pretty da** good. They get excellent bass off those 6x9's.. Here is link. They even have pictures on how to install and remove!
http://www.carstereohelp.com/
http://www.carstereohelp.com/