How Do Digital Amplifiers Clip?

This got me wondering how digital amplifiers clip and how an underpowered digital amplifier affects the speakers when over driven?

a digital power amplifier is a switching amplifier (a cousin to the omni-present switch-mode power supply in our computers). So, the output is toggling between plus/minus supply rail & ground. This switching waveform is filtered (usually by a LC filter or many LC filters, each of which is/are a 2-pole filter) to produce the average signal, which is the music signal amplified. As long as the input signal is within the power amplification limits the output signal switches with a duty cycle well below 100% & well above 0%. Once you start over-driving the digital power amplifier, the digital switching output starts switching with a duty cycle approaching 100%, which basically means that the switching output stays a long time at plus/minus supply rail for a much longer time than it stays at ground voltage. The average/filtered version of such a waveform is a (near) DC voltage at the output.
So, at clipping levels, the digital power amplifier will output high levels of DC that will be fed to your vintage speakers & THAT (the DC) will be the death of them. The tweeter usually has a high-pass network which means that it has a series capacitor that will block DC but the woofer (& even the midrange) does/do not have a series capacitor so DC will be fed directly to the driver & it'll damage very quickly, if not immediately.
hope that this helps.....

Many thanks, Bombaywalla. Helps a lot.

It's a good question. If my Class D amps have clipped, I have not heard it yet. Avoiding clipping like death is a big reason I went for 500w/ch Icepower amps. I like my music loud and my large OHM speakers are not particularly efficient (87db or so I believe). I've heard a lot of amps both SS and tube clip over the years. If the BC ref1000ms have ever clipped, I am not aware of it. Nothing I throw at them can seem to make them even break a sweat.

I have the bel cantos too. They have a soft clipping feature to smooth the waveform and cut output slightly as clipping approaches. I believe that feature is built into the B and O ICE module. Like mapman above I never run out of steam. I just keep turning it up and the soundstage gets bigger, deeper and wider.

Its manufacture specific.