Distortion doesn't kill subs. Power does . Distortion typically raises the power out of a amp a little and a clipped wave holds a much higher 'average" than a no clipped. For example perhaps a rap song you listen to unclipped although maybe running 1000rms after the dips in the recording and the wave you get maybe 300rms. Well when you heavily clip the wave now the amp may put out 1200 watts and although the total power only increased 20 percent the average power now due to it being clipped may average 800 to 1000 rms. 3 times the power . So does clipping cause the speaker to blow directly .. NO. But it is always associated with it because it does cause other things to happen to blow the subI am sure you can get a good bit more out of them. If you clip the signal a little it will not be harmful to the subs, only when you run 10-20% distortion will you start to mess up the sub. And I think you would get more power out of them running them individually and matching the gains, not to mention if you get the voltage up to 14v. But those are good results for a completely clean signal and 13v.