\ Thanks guys ...... The change in the pitch of the hiss with engine speed made me think it might be a ground issue.... Also, how it can come and go with a good bump in the road mage me think that way,, but I guess that could also be a bad solder joint in the guts of the amp.... This mounted in the trunk, so if I want to check the ground before resorting to buying a new one, where is the ground and how do I check it ??? Also, if I need to buy a new amp, any recommendations as to make and model ???? Thanks .....![]()