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

You can buy your own EPC GaN boards from Digikey, and yes they operate with no heatsink.
Because EPC’s Steve Colino said to me, (and I posted up his email), they are at 600khz switching speed, you can increase that to 1 or 1.5mhz as Steve said, but you will have to use a heatsink on them.

@georgehifi
Yes, the board itself is the heatsink, but is an evaluation board. If you ran this thing under heavy conditions, it would fail unless cooled by a fan or the output devices were mounted on a proper heatsink.

Heatsinks are required, even for Gan devices switching at lower speeds
If you ran this thing under heavy conditions, it would fail

And yes Gan devices have their own heat pad underneath which is sweated to the ground plane of the PCB. But that will be in every case that they are used in, your not going to twist it any other way.!!!! https://ibb.co/jTWd9nx

I tend to believe the manufacture of the board, EPC and it’s designer Steve Colino, who stated only heatsinking is required on these GaN devices if the switching frequency is raised. Not by what you say.

And from Merrill Audio who use the higher switching speed

" Internally the Element 118 Power Amplifier Monoblock PCB boards are manufactured to the highest excellence available and further engineered for sustaining a most stable temperature distribution. Using 8 pounds of pure copper per monoblock, the highly refined heat distribution system maintains a steady temperature environment on the PCB boards, a condition absolutely essential for linear operation."

I've ordered 4 Class D amps today to add to my listening list. I'm looking forward to stripping them down and tuning them up.

And from Merrill Audio who use the higher switching speed

" Internally the Element 118 Power Amplifier Monoblock PCB boards are manufactured to the highest excellence available and further engineered for sustaining a most stable temperature distribution. Using 8 pounds of pure copper per monoblock, the highly refined heat distribution system maintains a steady temperature environment on the PCB boards, a condition absolutely essential for linear operation."

George, looks like you made my point.

I tend to believe the manufacture of the board, EPC and it’s designer Steve Colino, who stated only heatsinking is required on these GaN devices if the switching frequency is raised. Not by what you say.

Well you're not likely  to be designing a class D amp anytime soon, so its no worries for you. For those that **do** design such amps, the idea of no heatsinks is scary to say the least, and the prudent designer that knows the amp is going to see some thermal abuse in the home will add heatsinks. To not do so is to court disaster- If it turns out that a model is overheating, the boards in the unit will have to be redesigned and that sort of thing can put a company under really fast.