I have a pioneer HU with 6 RCA outs- 4 for speakers, 2 for subs. Both amps are grounded to the same spot. What happens is when the subwoofer RCA's are plugged into the HU, I get engine whine through the speakers, even if the subs are disconnected from the amp. As soon as I unplug the sub RCA's from the HU, the whine stops. YET- When the sub RCAs are plugged into the HU, the SPEAKERS sound better (louder/more bass- mind the the subwoofers are disconnected). When I unplug the Sub RCA's from the HU, the sound quality from the speakers diminishes. What is wrong? Thank you everyone for your help.
