Rookie101

Can you use the Klipsch RF7 series for center, front, and side effect and RF5 series for rear? Would they match or should I buck up and get RF7 for rears?? Also I have a DenonAVR5800 receiver and I'm thinking of exchanging it for B&K AVR307 or going with B&K separates. Any thoughts please!! One last question, I have Mirage speaker set up now I know this is a Klipsch forum but what are your thoughts between the two? My complaints with Mirage is that when playing 2 channel they are not crisp enough for my taste. But the omni-polar technology is great for home theater. I trying to find a surround system that will give me the best of both. Please help with your thoughts and thanks in advance for your time. Marc