Can a power amp have too much power, risking damage to a speaker?

Yes, but the speakers will hurt you before you can hurt them.

"we often get out an audiometer to ensure the sound-pressure-level is well under 95dBA for sustained periods."

This would be less than ONE WATT fed to your Klipsch speakers. I think you’re good.

A little historical context:

When Bose 901s were first introduced to the audio world, they had a power rating of 270 watts (If memory serves correctly). They were having incidences of catastrophic driver failure. A quick study revealed that little Pioneer receivers (around 10 WPC true RMS power) were the culprit. These little boxes were, essentially, turning into low amperage DC power supplies at sustained clipping for long periods of time (hours). Bose raised the "recommended" minimum amp power rating to 50 WPC. Problem solved.

@waytoomuchstuff  That is exactly right. Too little power is more likely to do damage than too much, but there are some caveats that most audiophiles are aware off. With high powered systems it is stuff like dropping the tonearm on the record with the volume up. Or switching to a higher gain source with the volume up. 

waytoomuchstuff: old enough to be familiar w the Bose901power issues. 

To mijostyn and others who warn about TOO LOUD sound: We use an audiometer to monitor our listening room and most of our listening is below 70dB; if we are watching an action movie with lots of special effects, we find transient peaks of 100dB or more. A few minutes a day of over 95dB is unlikely to  cause permanent damage.

BTW, the new Apple Watches have an App that monitors SPL and seems to deliver readings pretty close to what I get from our more sophisticated audiometer. 

Doing some quick math here, your Mac and K'horns or LaScalas should hit peaks of over 130 decibels in your room. Should be plenty of dynamic range available on demand.

agree... with your math😁. And will not even approach 130db in our theater.