Did the sub come with the package? If not I would seriously consider something better. If it did, well, it's better than nothing. Whatever AVR you get I would set the crossover to no more than 60hz and maybe 40hz with that sub. Your speakers have quite a bit of bass on their own.
Anyway, to your question- Klipsch are easy to drive, I use a 45 watt AVR and it's more than enough. Get the AVR that has the features you like the best. They all pretty much sound the same. The only thing that makes them sound different is the version of automatic room correction software they use.
Many people like the room correction and some don't. Most here on this forum seem to prefer AVRs that have some form of Audessey.
Again, get the one with the features you want, whether that be a specific brand of room correction or built in wifi or BT. Power rating should be the least of your concerns when choosing an AVR.
Klipsch RF-62II, RC-500, RS-400, SVS PC12+,
Def Tech SC8000
Harman Kardon AVR 1600
PS3, Apple TV, Sharp 70" Qattron