Well to be honest, as someone that knows alot about the watts and RMS and all that, you want to get an amp where the RMS levels are around the same, the max power is only for a second at the most, I usually try to keep the max power of the amp under the max power of the sub. (IE 1200 watt max, 600 RMS Sub gets a 800 Watt max 400 Watt RMS Amp.) That way you dont have to worry about blowing your sub, and you also dont have to worry about the amp overheating unless you listen to your radio at 3/4 to full volume. I have a 1200 Watt Sub powered by a 300 Watt Amp, and Im getting more bass out of it than alot of people that have a 1000 watt amp with 1500 watt sub's around here can get, tuning the amp is the key, not how much power it can push. I would also recomend getting one with a lowband pass if its just for a sub, otherwise a standard amp will put the treble through to the sub as well.