Sorry to disagree, Matt, but it's the output stage transistors' clipping that does tweeter damage. A severely-clipped sine wave looks a lot like a square wave, and square waves are notoriously noisy.

A clipping stage ahead of the output stage will not pass the same damaging high-frequency noise. It's the output transistors' being driven to the point of saturation (full-on) that define's clipping. The amp output approaches the power supply's rail voltage. (Typically 0.6v drop)

Transistors are great devices while operated within the linear region, but they are less than ideal near either extreme of their voltage swing. Noisy near turn-on level (which is why the A/B class of operation is so popular, where both polarities of the output devices are never fully off at the same time.)

With class-A amps, neither polarity is ever fully off. The power dissipation doesn't change with loudness. This is the cleanest amp, but the least efficient. With class-C amps, one polarity is fully off as the other is at the threshold of conduction. Noisiest, but most efficient. Class A/B is considered to be a design compromise.

Lastly, a weak power supply can cause premature clipping because the supply voltage drops just when (and because) the output current is the greatest.

Larry
www.fineelectricco.com