I have a 95 Mustang Coupe that I just installed a JVC KD-HDR1 head unit in. I still have all the factory speakers installed, not the MACH system, but I do have a factory amp. After the head unit was installed, both the front and rear left hand side speakers are playing much quieter than the right side. The balance is not out of whack at all. Wondering if anyone has any insights into what the problem is. I had the JVC in my 92 Taurus just this weekend, and everything worked great, so I don't think it's the head unit.....any ideas?

 

Try bypassing the factory amp and see if that helps. You can use power from any source available when hooking up the headunit. Just look for switched +12v and constant +12v power supplies. You can run good wires directly to each speaker as well. I think it makes the sound quality of the system better. Plus if you want you can solder all connections.