They are not made for sound quality. And your setup can sound like shit for lots of reasons. I have owned the 2150 pushing a single 1200X and it was nice sound. I had the x over set at 70 hz and the boost about half way up, and the gain about 40% up.
Try lowering your gain, and BE SURE all your wiring is correct..
and make sure you are using 4 guage power wire for the (+) because it needs all the amperage itcan get. Caould also be a power problem as far as not being able to dish out the amperage needed.
THey have switching power supplies, so they can run full power @ 12.5V as easily as 14.4V WITH THE RIGHT AMPERAGE.
So look into your wiring, and if possible, test our alternator output in both voltage and amperage, then see