I have a kenwood head unit. it has a low pass frequency setting for the sub output. My question is this : If I have the low pass frequency set at 80hz on the head unit, Should I have it set at 80hz on the amps crossover as well ? or should turn the low pass crossover on the amp to the highest frequency, then adjust it using the low pass crossover on the head unit ? or set it to through on the head unit and use the low pass crossover on the amp itself ? Which way will give the cleanest loudest bass