Which Class D Amplifier? PS Audio, Ghent, Nord, Merrill or other???

 The EPC eGaN FETs switch 10x faster than silicon MOSFETs and have zero stored charge. I'm guessing that probably improves sound quality when used in a class D amp.

While they are faster its incorrect to characterize them as having 'zero stored charge'. The gate (input) capacitance is the big issue; on traditional MOSFETs it can easily be around 2000pf, which requires a bit of current from the driver circuit to switch the device at speed. GaNs tend to have less gate capacitance (about an order of magnitude less, depending on the device) and that is part of why they can switch faster. But that gate capacitance still plays a role in the driver design.
Much moreso than actual switching speed, getting dead time down is what reduces the distortion in a class D amp. Many of the GaN devices switch fast enough that amps with zero dead time can be built at pretty close to current switching speeds (400KHz or so).

Hello atmasphere,

     I think I understand; while GaNs do switch much faster than traditional MOSFETs they still require some driver circuit current to operate.  The use of GaN FETs results in significantly lower gate capacitance and stored charge but not to zero. 
     You're stating the most important benefit of using GaN FETs in a class D amp, however, is reducing dead time (possibly to zero at current class D switching frequencies.) since this allows for the further reduction of distortion.  It seems to me that the benefits of GaN technology will improve the performance of all types of ss amps, not just class D.
     Please let me know if I'm misunderstanding anything.
     I'm also curious about how your development of a class D amp is progressing and whether it will utilize GaN  or any other newer technology.  
     I'm very interested and anxious to actually audition and experience the performance improvements gained through well designed amps incorporating the best of existing and recent technology.
Thanks,
  Tim

ATI. Under $2K and uses Hypex engine with a beefy linear power supply

@singintheblues

check-out these Class D offerings as well. And 'no,' I am not affiliated with this company. I just own a pair and have talked directly to the owner / designer...had them since July 2017 and love 'em. I listen circa 6hrs / wk. PM me if you have questions
www.cherryamp.com

Here is a an email back to me from the US company "ClassDAudio" regarding the use of the new GaN Fet technology in any of their completed amps or very well priced Class-D kits they make, that use linear power supplies!!
https://classdaudio.com/amplifier-kits.html

"Hi George,

These will not be available in kits. These amps are complex and expensive to manufacture. We’re hoping to have complete amps ready maybe in about a month. We’re still finishing case design. Tom"

Cheers George