I took my questions from this board to them... Will 2 12" Kicker CVR12's be louder and better sounding than my 2 12" sony xplod's (300rms apeice) powered by an Alpine producing about 400rms per channel. They are in a sealed box and powered by a standard factory HU. His answer: NO. He says that before I do ANYTHING I would get more out of buying a quality HU than by replacing any sub or what not. Is this true? And what improvements will I get from a better HU. He said after I get that we could see if maybe certain subwoofers would sound better/louder etc. but he said the HU is more important.
Chris, he/she is partly correct. Sony makes lousy car audio products to start with. So if you're looking for loud distorted sound, then Sony might be good enough, but if you're after quality sound, then try other brands. Kicker isn't that great either. It is however much better than Sony crap. As for your stock HU, it probably doesn't come with RCA output jacks. This means, you will need speaker to RCA converter to power external amp. That will induce distortion and poor quality bass. The difference between stock HU and HU with RCA output jacks is almost 2x in quality.
It'll give you much more precise and tighter bass response. That CAN translate into louder sound. It's really a combination of great amp/sub and sub box. You can have the best sub in the world, but with a bad box, it'll sound like Sony. Not dissing your Sony, just telling you the facts.