My new review for The Absolute Sound comparing AGD GAN amps with BHK300’s

@atmasphere

To my knowledge only one company anywhere has made the claim that the devices they use are ’audio rated’ as you put it (although I am not sure they used those words, so paraphrasing). The only parameter that might make that so is the low output capacitance I mentioned. Beyond that, yes, the output transistors of any class D amps are designed for switching with power.

A loudspeaker is a motor. Also a transducer.

Output capacitance is really not a “thing” for class D amps, other than internal capacitance (parasitic) can effect the maximum switching frequency and possibly efficiency of the switching device, how much of the switched energy is converted to heat. That’s the only advantage of GaN devices; higher voltage, less heat, higher switching frequencies. It has nothing to do with transfer of energy to transducers (loudspeakers).

Im not a “naysayer”. I’m just a “factsayer”. I strongly dislike those manufacturers or reviewers who use consumers’ ignorance of technology to sell stuff.  These “proprietary” GaN “audio grade”devices grabbed and used for their singular audio use/purity is a “snake oil” claim. Pure and simple.

@wolfie62 Output capacitance of a class D isn't a thing as you say, but output capacitance of the output devices is. Its nice to have that low for better switching.

@atmasphere 

Output capacitance of a class D isn't a thing as you say, but output capacitance of the output devices is. Its nice to have that low for better switching.
 

Exactly what I already said. And “low output capacitance for better switching” is exactly my point!! Those output devices never see audio frequencies!! They are switching at much higher frequencies than the audio spectrum!!

So finally we are in agreement. The GaN devices are switchers and are NOT audio devices.