having both amps sound bad can almost immediately eliminate speakers and amps. So while you can still test them rather easy (external ipod hooked into a new set of mini to rca cables at the amp) i would suggest looking at the "bass" on the deck or the rca's. sounds like maybe you have some bad rca's (aka $1 store cheap) or you've got the bass boost on (eclipse doesn't have one i know), the bass cranked up high on the deck or something wrong with your crossover settings possibly.