Years agao I had the factory radio replaced with a ujit that played MP3's. It worked very well until recently. I went out 1 day to discover vthere was no sound coming from the speakers. Thinking the unit was defective, I purchased a new one from Best Buy. I removed the defective unit and installed the new one. It worked for about 1 week and now I have no sound again. Unit has power and there are no blown fuses. A friend suggested I bypass the factory amp????? Not sure if that is the problem or not but if it is where might I find it?