i have a 12 inch sub that is bridged & i hooked up may sub to my new amp.when i had both input jacks in i had the amp turned up to a level were the amp should have blown my speaker,but it hit just a little then i turned it down & took the positive jack out & it started to hit harder.i tried everthing & it does the same thing. does anyone knoe what i may be able to do to fix this problem?