To clarify here...
In this specific case, the "digital" description refers specifically to the switchmode power supply which operates on a fixed clocked ~50% duty cycle that does not change (except under a fault condition). There is no PWM involved, it is a purely a serial "data" stream. It's digital, as in if you looked at this signal on a scope, it would look exactly like a digital microprocessor clock, or a 50% duty cycle word clock that is used to syncronize digital data in digital audio.
There is another way to design an SMPS that uses a variable duty cycle and variable frequency switch mode control, probably better (or more accurately) described as a discontinuous signal or a continuously varying control signal. This is probably a more common method of control on today's class D amps because of the potential benefits in minimizing EMI emissions.
The NeoPak 3.5 amp itself is not digital and in fact both the preamp and power amp are purely non-switching analog. The digital term was used to help describe the mechanism that is involved with the power supply and is not for marketing purposes.
Originally Posted by Vince Klortho
I didn't realize how widespread this nonsense is. From the Genz Benz website on the 3.5 amp :
I think I'll return to ignoring the marketeers now.