i have a monoblock amp that's rated at 340w @ 4 ohm and 500w @ 2 ohm. my sub is a 12" single 4 ohm voice coil rated at 500w rms. is this a good setup? am i getting full 500w? if not, will i have to get a 2 ohm sub to be able to reach 500w? i will have to get a new sub eventually, so if you can recommend one that would be great. this is the amp i have http://mobile.jlaudio.com/products_amps.php?amp_id=557 any help is appreciated. - Josh