if HU means head unit, then i have an eclipse head unit... my RCA's are good... i have a 4 channel amp for my door speakers, and a kenwood on my subs now. all works and sounds good. picked up this amp today for a good price and plugged it up... nothing happened except the power light came on... plugged back up my kenwood and my subs started hitting again
Sounds like the amp might be a dud but you could possibly confirm this with some measurements on a multimeter. Check the O/P stage and see if you're even getting voltage. Try switching between filters (LP/BP) if possible. It could be a messed up filter stage, too.