GaN-based Class D power amps

The use of GaN-based power transistor tech is now emerging for Class D audio power amplifiers. Seems appropriate to devote a forum thread to this topic. At least 3 companies have commercial class D amps in their books:

Merrill Audio, with their model Element 118 ($36k per monoblock, 400 W into 8 ohms, 800W into 4 ohms), Element 116 ($22k per monoblock, 300 W into 8 ohms, 600W into 4 ohms) and Element 114 (coming soon).

Review of Element 118 at this link:

ADG Productions, with their Vivace Class D amp ($15k per monoblock pair, 100W into 4 ohms). (The designer emailed me indicating he has another product in the pipeline.)
Review of the Vivace Class D moniblocks at this link (warning: link might not work (1/11/2019)):

Technics SE-R1 Class D stereo amp ($17k per stereo amp, 150WPC into 8 ohms, 300WPC into 4 ohms)
Preliminary review of the Technics SE-R1 at this link:
Technics also has a lower priced GaN-based class D integrated amp in their catalog:

Anyone listened to or own any of these amps?

PreviewAg insider logo xs@2xcelander

Hello Celander, the Vivace's home page does not seem to list input impedance.... Perhaps Alberto Guerra can chime in on the subject.

Saluti, Guido


Enjoy the board then. I’ve got higher standards.

Please list all the item no.’s in the BOM list I posted that you or someone else would improve on, and with what and why?

Cheers George
GaN can generally handle higher voltage and has smaller die area thus lower capacitance and easier to switch. A silicon carbide substrate will better heat transfer as that material is better than silver in conducting heat.
The "sound" is in the digitizer and stability of the power supply. Peak loading of the power supply will cause the same issues as any power supply.
There is no real advantage in class D unless you (really) need a lot of power, like driving 50 speakers to earpiercing levels or drive an electrodynamic shaker for environmental stresstesting where 30 KW may come in handy.
Of course as people have reported here they can be made to sound as good as other types, with more effort. So really why use class D? There is no real advantage, just more complications. 
We are testing different input impedance values for the best result in all situations. .Once the final number is settled on I’ll let you know..

@ George, you know that there is a customer base out there that will not buy basic box components. There are also designers with design aspirations beyond rudimentary boxes of bent steel sheet metal. Being that I am a manufacturer and dealer I have plenty of buyers that do not buy anything that looks like a sheet metal box .So there is nothing wrong with a pretty box at a premium price. You must absolutely hate fine art. You know that Rembrandt is just antique canvas and old wood framed up with a few pence of oil and pigment. Levis jeans are $50 and they are the same dang thing as a Chinese pair of denim jeans for $15. As an importer of the best Chinese audio product currently being made in many peoples opinion, I can tell you this. Chinese tune product differently than America and Europe. You can have a dead nuts clone from China of a DartZeel and it will not sound the same. Plus there is this thing called pride of ownership. and some of us have it. Ive spent a good amount of my career trying to find the Chinese equivalent to the world class or even semi world class, and Ive not been able to find it. Look, the same things piss me off that piss you off. For me though it has to be more blatant, Like a $36K Mono with a chassis cobbled together using everyday, off the shelf parts. again, we could pick anything apart we want to as a waste of money. So some people want $2K Monos with a basic box from China, others want something with similar parts but made in USA and produced inside a piece of functional art. Neither one is wrong,.So please lets not vilify those that value different features than we do. These forums have a very bad reputation for crap talking bordering slander that ends up crippling this place for use as intended which is to be a place where new audiophiles can come and feel welcomed. As well as where manufacturers and dealers  can interfece with the potential buyers without fear of damaging allegations or otherwise generally negative comments about us. Its why I rarely come here. We already fight the stigma of the 1980s stereo salesman, lets not keep that crap alive, I say we snuff it here and now. We will all come down for a walkabout with our favorite Cobber and sit around the campfire eating Barramundi, OK ? .
You must absolutely hate fine art.
I buy audio equipment first and foremost for it’s sound, second comes price, last is looks.
I’m not one of these that sets up his "glitzy chassis" multi $k equipment in between the speakers on just as "glitzy" racks, so I can gaze at it in wonderment and say to myself wow how good it looks instead of listening to the music. And at the same time all that "glitzy" equipment your gazing at is ruining the stereo image and depth.

Cheers George