Until last year, an HK AVR had always powered our theaters. We have been through many models and all have served duty powering various Polk Audio speaker packages. My ears always enjoyed the combo of the two brands and our last build was quite impressive...considering we really did not spend that much money on it.
HK AVR 3600 (I was lucky to not have one riddled with issues)
RTi 10's for mains
CSi5 center
RTi 6's for surrounds
2 Paradigm PW2200 subs
Off of the HK's power, this system sounded pretty damn impressive. I expected less...mid-market gear and all. Otherwise, I thought the system was (imho) an over achiever for what I paid. Clear, crisp, punchy, and nothing truly out of sorts. Eventually, I added an ADA PTM6150 amp to the rig and it made for one heck of a system.
In the end, I gave credit to something way beyond the gear in the room. The sound was above average to me due to the pointers I took from forums that helped me to prep the room. Treating the walls/ceiling, bass traps, choice of furniture cost me some coin and drove the wife nuts but having a neutral room to work with makes ALL the difference in the world.
I have since moved away from HK and Polk but I will never forget how great I thought they sounded together in our homes. Just my .02 and happy hunting.