I have a kenwood mp532u head unit with the USB attachment and surprisingly it only 2 sets of RCA's rear and front. I have 1 subwoofer and 1 amp for the sub and the highs are pushed by the HU. I was told that I could connect the sub to the rear and fade it to just the subwoofer for more bass. If I use the bass and have it maxed up the speakers become distorted. Can you fade it to the subwoofer only? I tried that and it faded the speakers. The amp has input and output RCA's. I guess I can turn the amp all the way up and have the bass in the center->(-0+)or at 0 if needed too. I want to keep this HU and not have to buy another but the sub is not loud enough without distorting the speakers. Thanks!
Aside from buying a new head unit, the best thing to do would be to just buy external HPF crossovers for the speakers being powered by the internal amp-that way you could leave the bass turned up so it wouldn't cause anything to distort and the sub could still receive the low frequencies.