I have two JL HD600/4's in my car running two sets of Audison AV-K6 VOCE's. They work incredible. I have never heard better sound out of anyones' vehicle. I've never had them get even warm on me. They run nice and cool and smooth. I don't know how the other versions work but if I wanted a JL amp to power my subs I think I would go with the Slash 1000.