So, from the Klipsch site they say that the RB 61s will handle 100W RMS / 400W Peak. Since your receiver outputs 100W/channel, you shouldn't have any problems blowing your speakers.
Punkmonkey's advise is correct, however, you may be using these adjustments incorrectly. It doesn't seem likely that you should be hearing more detail simply by adjusting the output volume for a specific speaker to +12. But, if it sounds better to you, then more power to ya.
