I just received a new amplifier for my Mach 460 system, it's the same one I had in there before, but I noticed that when I plug it in and use the door subwoofers, they are a lot louder than usual and starting voilently shaking my doors. I have to turn the bass setting down to -4 to get them to be normal when before I had them on +3. Is there a setting on the amplifier I need to change? Help!?