crackling noise at high volume

For those worried about distortion this is quite normal...the tweeters used in most two ways will compress at high levels. 95 db SPL at the listening position is a bit much for most consumer designs. Piano is a good way to hear it becuase the piano is a percussive instrument. Thi susally does not damage the tweeters...provided you don't over do it. Many people listen to this type distortion for years without realizing it....they just think the music is too loud for their ears and do not realize it is the speaker.

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.

OK, Eldarrford, Thanks for the input...amp power rating greater than speaker program rating doesn't eliminate the possibility of being able to drive the amp into clipping.

What destroys tweeters is almost invariably amplifier clipping. The tops of the waveforms are clipped off by a lack of voltage in the power supply, and the result is a squarewave or(almost)DC arriving at the tweeter that fries it. That happens when you're trying to get more power out of the amp than it can deliver. What you've probably done is exceed the linear range of the woofers(driven the voicecoil out of the magnet structure or bottomed it out in the magnet structure). If they still sound good at lower volumes, don't sweat it! I've done the same thing to my subwoofers with some sloppily recorded source material from time to time. If you want higher SPLs: Get more efficient speakers and/or some that can take the output of your 100wpc amps.