Ghosthouse...You are correct that "Clipping" refers to the "clipped off" (square) tops and bottoms of the music (or sinusoidal test signal) waveform which occurs when the waveform peak voltage exceeds what the amp can put out. However, the speaker manufacturer's recommended power amp rating has nothing to do with how much power you can apply to the speaker. The manufacturer is telling you that higher power may result in damage. It would be easy to clip a 100 watt amp driving these speakers. When you do that, an unusual proportion of that power is at high frequency and gets routed to the tweeter.
Most dome-type tweeters can take some punishment, although I have succeeded in blowing out several. The ribbon tweeters such as used by Magneplanar are more fragile, which is why you never want to use a low power amp with them.
