I don't know that those Klipsch speakers will benefit from the extra power, but XenonMan's idea of testing the idea out with two other channels on the 7700 is a pretty good one.

There's one potential problem that I can see. Since you're already using a 7.1 setup, you can't use the "bi-amp" setup without abandoning your surround back speakers. That means you'll have to use the XLR and RCA left/right front outputs to bi-amp. The XLR outputs will have a higher level than the RCA outputs (that's the nature of XLR), and neither the 7700 nor the 2200 have any sort of user-adjustable gain control to compensate for that.