im thinking about getting either one 15 sp4 or 2 10 SSDs I am running a old school lanzar opti drive 2000D amp nothing but true power! but I want to know what level entry is the sp4 and ssd? what set up will be louder?! what one will sound better? I know 15s get deep and 10s get punchy and loud Right now I have a dc level 3 15 and 3 type rs all old school. But im stepping down for something new, So one 15 sp4 or 2 10 ssds?! BOTH will be in ported boxes! and powered on the same amp! I do have a solid power with volts. which will be louder and what will be better sq?