First off take a DMM and set it to ohms and find out how many ohms one coil has... unless it is written on the magnet... you are saying that its wired at 3 ohms, which could be the case if it is a 6ohm DVC wired in paralell... then my next assumption is that the 3ohm load is then wired in bridged mode on your amp... except that in bridged your amp is only stable to 4ohms... if that is the case the speaker will be drawing in excess of 300rms, the question is for how long...? anyway enough of my banter find out the impedance of the coils and someone can sort you out