Even if at 400% volume the hardware shouldn't let through as much power as to blow the speakers. The waveform should be amplified and clipped to a safe value. The same applies to this Mac. If they know the sound chip can be tricked to send too much power, fix the sound chip or pick another one. If they didn't know, they didn't test their product.
Interestingly I have a Dell Chromebook 13 running full blown Linux and I am observing speaker distortion. It doesn't matter to me that much, but a bad driver could definitely cause damages to hardware.