y do you need an amp at 4ohm, when you have a dual 4ohm sub, what you really need is 500rms at 2ohm since you wire the coils in parallel it goes to a 2ohm load and is in 8ohm when you wire in series.. with the amp you are buying you will only be able to power each coil since it is a 2chan amp meaning you will only get 300 watts out of the amp... pm me if you're confused..