guys. I'm a home theater/hifi nut. I will happily pay for sound quality etc, however, when we are talking about a car audio sub....give me a break. as long as the power is there the sound quality will come from the box and the driver you are using FAR more than the amp behind it. if the THD is equal, and they pretty much all are, you are not going to notice a difference.
in fact, I would put my money where my mouth is and GUARANTEE you could not hear an audible difference from one amplifier to the next when playing the same sub in the same enclosure. I'd love to test the JL, Alpine, and Pioneer on the same subs/box with the same settings. The ONLY difference you'll notice is that the Pioneer has more headroom and will play much louder since it's delivering TWICE as much raw power to the driver.
I'm not trying to start any arguments here, and it is possible that the JL and Alpine amps are built better in some way (better caps etc) I dunno...but what I do know is that at half the price and providing twice the power the Pioneer was an EASY choice for me.