Question on "klipping'?

Clipping occurs when your amp can't provide either sufficient voltage or current to drive your speakers to the desired listening level. A higher impedance load and an amp with lower (internal DC) voltage supply level might tend to run into the voltage limitation whereas a lower impedance load and an amp with higher internal voltage supply might tend to run into current limitation. Obviously, there are many possible combinations. An important consideration is the efficiency of your speaker and the sound levels you are trying to accomplish in your listening environment. When you drive your amp to voltage or current limitation, the clipping or limiting of the output is a sharp tansition in the output waveform which generally generates high frequency transients or "spikes". This is why people with low power amps often blow the tweeters in their speakers and can't understand why. It is usually the amp limitation, not the speaker.

Nicely put Sndsel, this is also what i found on audio electronics glossary: Refers to a type of distortion that occurs when an amplifier is driven into an overload condition. Usually the "clipped" waveform contains an excess of high-frequency energy. The sound becomes hard and edgy. Hard clipping is the most frequent cause of "burned out" tweeters. Even a low-powered amplifier or receiver driven into clipping can damage tweeters which would otherwise last virtually forever. Hope it helps!

The amplifier controls moving the speaker in and out. When the amplifier gets overworked it pushes the speaker yet doesnt have enough power to pull it back. It is well explained above and not only does this happen with less power amps but I think it is actually more common with less powered amps.