i just talked to a guy that has a hifonics 1000 mono amp and this is what he said

my amp would barely play my subs aswell, i couldnt really hear the subs hit but if u popped the trunk open and felt them they where moving a tiny little bit....i tried new RCA cables and it did nothing, i still drove around with it hooked up and on some bumps the subs would kick in so i knew it was some sort of loose connection, i took the acces cover off the back of the amp and let the stereo play as i poked some objects around, i eventully found my loose connection and i still need to re solder it


thats the same thing happening to my amp.

 

got it fixed it was a couple things not working right i kept trying and got it to work i managed a 143.1 stilll needs alot of tweeking .. and if i was using the right frequency lol