If you've got 6000bucks to play around with I would get something better than Hifonics for an amp. Look into Viper Audio 2500d, US Amps 2000, Crossfire Vr2000d, Directed 2400d, Orion 2500d, Zapco... With two XXX 15's and that kind of power with each sub, a big *** ported box (5cuft per sub) you'll probably go deaf very quick, that's gonna be hitting some insane numbers...