A true class 'd' amplifier required a digital input a pwm amplifier uses pure analogue inputs.
The Devialet amplifiers are true class 'd' they have analogue inputs however they use an ADC to convert the analogue into a PWM bit stream so the amplifier can accept that format.
From that point onward the principle is the same, similar to the way dac works with the end result subjected to a low pass reconstruction filter from between 36Khz to 120 Khz dependent on manufacturer design criteria.
The incoming signal is up-sampled / up converted to a high frequency (hopefully over 500Khz) so the any noise is spread outside the pass band and will not be audible, they finally going through a LP filter which delivers your signal to the speakers.
I could go through so many variables on how, what and why they work or sound anodyne or bloomy lol but I do not have time today.
Some people love em others hate em, done correctly they could sound absolutely up with the best amplifier classes available, other models can sound total phish.
The future is moving more and more to this way due to efficiency, smaller footprint and costs.
One other feature of PWM amplifiers is that when looking at signals on an oscilloscope say a 4Khz sine wave, the resultant image looks like it has a beard attached to it, this is the high frequency noise that you cannot hear sitting on the wave form. Some people find it puts them off.
Some light reading lol
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