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.....