What amp would i need to run 8 speakers in my car?

I hope this doesn't post twice, I have currently in my car two pioneer 6x9s (40 rms per) and 4 pioneer 6.5 (around 50 rms per). These are running off my head unit right now and i'm guessing the are seriously underpowered as my HU puts out 50x4 peak. (Pioneer deh-p3100ub) I also have two more 6x9's i would like to install i'm unsure of the rms but the peak is 150. i want to run all 8 speakers off the same amp. Which amp would let me get say 40 watts on one channel for 2 of the 6x9's, 50 watts on 2 channel's for the 4 6.5's and like 35 watts on the last channel for the other 6x9's? Or is my thinking all wrong? Is my HU giving me enough power and i need to upgrade my speakers? I'm kinda new at car audio so i have half educated guesses at this, all help is appreciated. Thanks.