Which ones are you talking about? The older Jl500/1, 1000/1, 300/4 are all awesome amps, they can handle 1.5 ohms all the way to 4 ohms. Very solid amps, put out very clean power. Now the new JL500/1v2 amps are even better, the v2 have are 50% at dissipating heat, are stackable, maybe a bit smaller, etc etc.