I am currently running a Yamaha rx-a3010 receiver with my gear, connected to an ATI AT 2007 amplifier with all Klipsch speakers. Any higher end Denon, Yamaha, or Panasonic receiver will work with or without external amps as long as if using the receiver it is rated at 140 watts or above. The Klipsch are very efficient speakers and easy to drive. If you look at amazon you can get an RX-A3010 for pretty reasonable as its last years model but that said it was still Yamaha's flagship for the year. I get to seriously loud levels with the Yamaha at -30 on the volume scale. In fact it works so well I bought my wife a RX-A3010 at Christmas and she loves it and it drives her polks with ease, but again the Klipsch are even more efficient then the polks.
ATI AT 2007 amplifier (200X7)
Klipsch RF 63 (main)
Klipsch RB 61 II (front heighth)
Klipsch RC 62 II (Center)
Klipsch RS 52 II (surround)
Klipsch RS 52 II (surround back)
Yamaha CX-A5000, ATI AT 2007 Amp (7X200W), ATI AT 2004 Amp (4X200W)Klipsch RF 63's - Main, RB 61's - Front heights, RC-62 - Center, RS-62's - Surround, RS-52's - Rear Surround, 2 Rythmik DS-1510 DIY Subwoofers (With PEQ600XLR3 Amp) each connected with Antimode 8033S-II, Oppo BDP-95, MMF-7.1, Project Phono Box RS, XBox 360, XBox One