Engine noise..

So I just installed a Soundstream Dtr4.500 and wired only two channels so far to two tweeters and two horns, I'm running the signal from my mono amp which gets it's signal from a Stinger Line out converter, I've grounded all places possible, changed the RCA's to straight to the line out and there's still the whining noise. The sub has never had any distortion like this, probably since the low pass doesn't pick it up. I also even bought into the "ground loop isolator" by Stinger, but the problem is still there just as badly. What should I do?