Unless I'm badly mistaken, clipping is what you get when you try to get too much volume from not enough power. In other words, the amplifier can't keep up with the demand for power, and the louder parts of the signal get flattened out (picture a sine wave that's flat on the top and bottom...) because there's no more juice. This is really bad for speakers, besides sounding distorted. Speakers driven too hard with a weak amp tend to get burned out faster than when driven to the same level with a powerful amp because of this signal distortion.
Damaged speakers also sound bad, (Understatement!!) but I'm not sure how to describe the sound. Maybe like paper fluttering in the wind?
