It is tempting to under-specify an amplifier on the assumption that less power means less risk to the loudspeaker. In practice the opposite is usually true.
What clipping actually does
An amplifier driven into clipping stops producing a clean waveform and starts producing something closer to a square wave, rich in high-frequency energy. That energy lands on the compression driver, which was never designed to dissipate it continuously. Drivers far more often die from a small amplifier being pushed than a large one being used sensibly.
Designing for headroom
Headroom is the margin between the level the system normally runs at and the level at which the amplifier runs out. Designing for programme material with genuine peaks means specifying for those peaks, then setting limiters so the system cannot be driven past them.
