Receivers
Read the Audioholics reviews of the Yamaha RX-V2500 and Denon 3805. They are both very capable mid-fi receivers in the $800 price range. Both also have new models out with extra features like HDMI switching.
The yamaha in perticular, is know for having a transparent pre-amp and amp stage which should work well with any speaker. To compinsate for the speakers response, both units have Parametric EQ functions.
Since Klipsch speakers tend to be very efficient, you probably won't need an external amp for your system.
Also, since budget is not a major issue, you might consider room treatments to optimize your setup. Rugs for the floor and drapes would be a good start.