" Just had to put that in there.... that ’someone’ being me...
Class D was first demonstrated during the vacuum tube era. The reason it is called ’class D’ is that class C came before it and so was already taken. PWM (Pulse Width Modulation) is an analog technique. Just ask any keyboard player with an analog synthesizer (by varying the pulse width, a string sound can be obtained from a square wave)."
Believe me I know exactly what "digital" and "class D" mean, and that class D is not "digital" - however, my point was that from the marketing perspective there ARE "digital amps" which almost all use class D but also include a DAC and purportedly the audio waveform never enters the analog domain, other than as a PWM signal, inside the amp - hence the amp itself gets the moniker "digital" amp and "class D" is conflated with "digital" when in fact the amplification itself an analog process controlled by digital microcontrollers.
However, would you agree that what you just excerpted about PWM describes a process whereby the waveform (square wave being the trigger for lack of proper terminology at the moment) is a combination of ON or OFF states in an array of switches (transistors or vacuum tubes) and that ON = 1, OFF = 0 which would easily lead people to assume that the process is "digital" even when it was a plain square wave and not a complex microcontroller dictating the ’sampling’ process?
Finally, would you agree or disagree then, that today's class D amps, with built in DACs and which use complex microcontrollers to sample the output and alter the switching algorithms can indeed be called "digital amps"?