Somewhat depends on your budget. You might check out a Marantz pre-pro like this
https://www.accessories4less.com/make-a-store/item/marav7701/marantz-av7701-7.2-ch-networking-a/v-preamp/processor/1.html and maybe pair it up with an amp like one of the Monoprice Monolith amps, depending on how many channels of amp you want (but the best deal is their 7 ch amp, even tho you only have 5 speakers maybe you'd want to expand later). Depends on what features/connectivity you want....
Another way to go is to get a receiver, and would be more cost effective than separates and equivalent audio quality, then add amplification if even needed, the Klipsch speakers have relatively high sensitivity and don't need tons of power (depending on your distance from the speakers and how loud you like it ... try an spl calculator
http://myhometheater.homestead.com/splcalculator.html ). For avrs I'd look at Marantz and Denon models personally, maybe Yamaha.
I'd pass on the Klipsch sub, there's much better out there from SVS, Hsu, Rythmik, Power Sound Audio and other specialists.
Welcome to the forums...