I have some questions to ask about some sub woofers. Which sub has great quality and which one has louder bass? (Kicker S15L7 15" L7 Sub woofer Dual 4 Ohm) or the (JL 13W7 13" W7 Series 13W7-D1.5). What is a good amp to get the best quality out of two kicker l7 15s? Is diamond audio better for...