really depends on the amp... lower quality amps are over rated and higher quality amps are under rated. for instance a jensen 500 watt amp is probrolly pushing a true 150-200 watts. as opposed to a ppi amp rated at 500 watts is going to push probrolly around 7-800 watts. hence why theres such a difference in price. if you a little more specific on the brand amp you are getting i would be happy to help you choose the best one. also what is the impedence (ohms) of each of the coils on the subs?