How do I find the proper sized amp?

You can always go with a bigger amp, but you MUST WATCH YOUR GAINS in that situation. as for amp size with those speakers i would try and stay around the RMS or maybe split it, if you can find an amp that has 125 watts RMS that is what i would go with.

mben: so you're looking for a 4-channel amplifier? 1st: stop even looking at the peak power - it means nothing. 2nd: a doubling of power only gains a max 3db increase in SPL. 3db is small. So, you'll barely hear any difference between a 50x4 amplifier and a 75x4 amplifier. 3rd: as long as you aren't an idiot with the volume control you can get an enormous amplifier. 4th: do take care to set the gains correctly along with not being an idiot. If you run your amplifier into severe clipping and are running a large amplifier for your speakers, there will be problems. I'd be looking the highest quality 50x4 amplifier you can afford. 50w is more than enough for components and the probably 200w bridged is fine for your bazooka. Then, if you need a larger subwoofer in the future, go with a separate class D amplifier. OR run it off the 200w bridged - you'll probably be happy with it. Again, the actual audible difference between 200w and 500w isn't large. New Project: 2003 Pathfinder