Hello, I would like to know what is best to set up my subwoofer and amp. I have A Kenwood X769 head unit, Crossfire CFA602 amp for my 2 12" Infinity Referance 1232w subwoofers. On my headunit I have a built-in lowpass crossover for my sub preout; 50/80/120Hz 12dB/Oct. On my Crossfire amp i also have a lowpass crossover at 70/100Hz 12dB. Which crossover should I use, the amps crossover or the headunits crossover?