underdriving a speaker won't hurt it unless your pushing your amp/headunit to its limit and clipping than it ill hurt your speaker, but if you have a 300watt amp lets say and you have the gain down to run only 100 for speakers and the speakers are rated for 200, you won't hurt them :P but whats the impendence of these speakers, you can run them at different configurations but 2 is probably the best
i just wanted to clarify to underpowering thing im not trying to pick a fight and start an argument its just been debated so many times and everything underpowering doesnt kill speakers clipping the signal does
but thanks for the help, i realize bridging speakers onto 1 channel onto a headunit is a terrible idea, probably kill the headunit that why i suggested i use the amp