well... although many would probobly argue me on this, the JL can be a more powerfull amp in some situations. The JL does 500x1 rms at *0.05* distortion at 1.5-4 ohms while the JBL does 600x1 at *0.1* at 4 ohms and 1200x1 at *0.1* distortion if your running 2 ohm... sooo if your in the 3-4 ohm range i would argue that the JL will be more/cleaner power. Everyone seems to think that harmonic distortion doesn't matter in the world of car audio for some reason because you "cant hear it". Well, the fact is, if an amp is rated at 500 watt per channel rms at 0.05 distortion and another is rated at 500 watt per channel at 0.1 distortion, what do you think the rating would be on that amp that does 500 watt at 0.05 when its pushed up to 0.1? If JL was to rate the wattage the same way as the JBL amp it would be much more. All in all, keep your JL amp. Its stronger then what meets the eye and has more features.