Adire Audio Shiva only comes in 8ohm DVC(wire it down to 4ohms)...so you will only be seeing about 1/2 the power out of the JBL 600.1, due to the fact that it maxs out at 2ohm's. Dan Wiggins of Adire tested the sub at 600 watts RMS. I would get an amp that will give you 500-600 watts @ 4ohms. The Shiva is a nice sub, the only downfall is that it was originally made for home audio applications, so it requires a bigger box...I wouldnt go below 2cu^ft per sub sealed.
my $.02
Sean McL