Do ClassDAudio Amps Have Proper Decay Of Notes?

BTW, someone said that Class D is not "digital" which is partly true, but PWM is a digital signal processing technique, so it's understandable for those amps to be called "digital" especially from a marketing angle.

The term "class D" is sometimes misunderstood as meaning a "digital" amplifier. While some class-D amps may indeed be controlled by digital circuits or include digital signal processing devices, the power stage deals with voltage and current as a function of non-quantized time. The smallest amount of noise, timing uncertainty, voltage ripple or any other non-ideality immediately results in an irreversible change of the output signal. The same errors in a digital system will only lead to incorrect results when they become so large that a signal representing a digit is distorted beyond recognition. Up to that point, non-idealities have no impact on the transmitted signal. Generally, digital signals are quantized in both amplitude and wavelength, while analog signals are quantized in one (e.g. PWM) or (usually) neither quantity.

" 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)."

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"?

An amp that I would consider to be a true 'digital amp' would be one where the process of conversion from digital to analog happened only at the output, IOW that the entire circuit is one big DAC.

@atmasphere - interesting.  I could be wrong, but my reading of the Lyngdorf integrated (and other "digital" integrated amps that are now coming out such as the new NAD DirectDigital) would seem to match this architecture.  As best I can tell, there is no "analog audio stage".  It seems like they are using the actual digital pulse output of the DAC chip to drive the amplifier output transistors.  In this sense, the amplifier power output stage is essentially acting as the "DAC I/V" stage (basically bypassing all the analog and preamp stages in between).  It's really not a "digital amplifier" because it is still an analog translation (which is required in any sense of audio anyways).  I could be completely wrong here, but this is what I am assuming based on how they are describing the product. 

I'm not sure how well this actually works.  Some people just love the Lyngdorf, but I would actually want some sort of Class A discrete analog stages in between to help shape the sound and reduce the square wave effect of the DAC pulses - in addition to providing a very strong signal to drive the impedance of the amplifier.  I think the Lyngdorf could be very crisp/clear sounding for some people, but I think it could go too thin and solid state sounding.