Well I just installed my Alpine 9830 in my 92 Mustang after the car sat for the winter. I took out the old HU and I noticed the factory amp for the Premium sound has been removed. Now I hooked the plug up to the correct one and everything powers up ok but I have no sound. When the HU was out I noticed there were about 5 or 6 extra plugs that were all unplugged so I never messed with them. Could this be my problem? Should I try plugging them into one another?