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

I have a pair of B&W speakers that have a recommended power of 50 to 300 watts. I'm driving the pair with a 120 watt tube monoblock amp attached to each. Other than having to chase down a ground loop issue (which I solved the other night), this setup is flawless. It may be "underpowered" but sure does not sound like it. I may build two more monoblocks and Bi-amp the speakers, for now, I have no need and it sounds amazing.

@joelepo wrote:

I have a McIntosh 402, rated 400 watts continuous per channel. If I use it to drive a pair of Klipshorns or LaScala [specified to handle 100 watts continuous] or similar high-efficiency speakers, do I risk damage to such speakers?

The La Scala’s are just around or slightly above 100dB’s measured sensitivity, and so would be very loud even with limited power supplied by the McIntosh; practically you likely won’t get to where your speakers are challenge thermally let alone mechanically, whereby the power in reserve will come in handy with loads of headroom (which is a good thing). However, something tells me the La Scala’s thrive on tube-based amps, preferably moderate to higher powered variants, so that might be worth experimenting with.

With inefficient and passively configured speakers in general (and most are), I’d recommend at least double the amp output power of the speaker’s long term max. power handling capacity. Less SPL requirements/shorter listening distance/more lively damped rooms can do with less amp output power.

Efficient and typically passively configured speakers of yore/vintage origins or inspired (with lower to moderate power handling) seem to thrive on and get by with low powered amps, tube-based in particular, whereas more modern and pro segment high efficiency speaker designs with larger voice coils and stiffer suspensions like to be fed by high powered SS amps - they simply come better and more assuredly to life this way, not least actively. Both approaches have their strengths; the former can come across seemingly a bit more lively and with more character, while the latter has the more solid and, to my ears, "neutral" and resolved imprinting. I prefer the latter camp for a variety of reasons, but I can appreciate either approach.

Thanks all for contributing to my education.
I play guitar and 5-string bass and have one Fender Pro tube amp with twin 10" speakers and a Fender SS Bassman with four 10" speakers. Guitar amps and speakers differ from high-fidelity amps and speakers. The former are designed to "produce 'music'" -- so as long as they hold together and generate the sound the musician want, all is OK. In contrast, seems to me that "high fidelity" speakers should not contribute any of their own voice to the sound that comes out. I KNOW... achieving that ideal is far more complicated than that. 

I've been playing electric bass for decades and I have a couple of pro bass amps (15s, 12s, mondo pro sub) and one learns that there's obvious limits on how loud you can play before the speakers get annoyed. Is this too basic? Over 6 maybe? Electric Bass teaches an interesting tone exercise.

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.