Both these brands are carried at circuit city.. Check them out there! I had this same debate in my head for a while.. The Polks seem to have a bit more bass to them, well, a lot more bass than the infinitys which seemed like the produced none at all.
Overall I decided with the Infinity 6010cs.. They played KMFDM a lot better than Polk IMO, a lot clearer vocals than polk it seemed,perhaps from the lack of bass?(woulda gone for the kappa perfects but they dont fit my application >.
-Lurius
PS: My opinions are based on the 6010CS vs. Db650's