Couple of things to point out about this thread- 1) The RMS rating is NOT a power requirement, nor is it any indication of how loud a driver will get with a certain amount of power. I has no relation to output whatsoever, it is simply a thermal rating of the voicecoil, nothing else. Do not base anything output wise off of an RMS rating, period. 2) The nominal impedance is an average rating, your overall alignment determines the final load the amplifier sees. Don't assume that an amplifier will be putting out half the power if you double the driver impedance. 3) There is no such thing as underpowering...