As of right now, I am running a Denon 2312CI receiver with TSi300 fronts and a CS10 center channel and a Klipsch RW-12d subwoofer. I saw an ad on craigslist for 2 Polk Monitor 70 front speakers and a CS2 center channel all for $300. Everything is in good condition and works well. My question is, would these speakers be worth the upgrade for me? Would I really see a $300 difference between the 2 speaker sets? And if so, would my Denon be able to properly drive the Monitor 70's pretty well?