Class D amps that are superior to all or most?


Recently, I have heard about some Class D amps that may be close to the best there is regardless of class. Certainly, this technology has been in development for decades. The main issue has always been the switching power supply. In this regard, I have taken notice of AGD. They have created a whole new power supply that “switches” at a frequency 100 times the normal silicon based MOSFET. The designer uses a gallium nitride based PS. Interesting, it is enclosed in the KT88 glass envelope that sits on top of his amps. I am aware of two more pricey amps that seem to be also at the top- the Solution and the Merrill. There must be others that compete for the title. After my thread, “Is there a SS amp that can satisfy a SET guy?”, I am still on the quest.
Don’t want to spend $50K!
mglik
I should mention that new gear got powered for a full week before listening. Amps got a 24hr 10% power burn-in on a load.

I travelled overseas a lot, sometimes for several weeks. ALL gear off and unplugged. 24 hour toast up upon return, then back to 20 minute warmups
Hello mglik.  The AGDs are great amps. So is the Starke Sound AD4-320. Four channels, great for electronic crossovers and two way speakers. Priced reasonably. You can return them if you are not pleased. They use a "conventional" (non switching) power supply. 
The Starke Sound AD4-320 is priced reasonably at $1300, i almost bought one in Dec. when they were on sale for $1000.

For me the AGD's are SOTA and that's what i'm after.
Kuribo stated:
"You really are clueless if you think all Bruno did with the Purifi design is "tweak" a few parts."

Where did I state this? I already stated (maybe you cannot read?) that tweaking is ANYTHING that improves the sound and performance....including circuit changes. Bruno makes it clear what design changes he has done to take his Purifi module up a tick or so over the NC500/NC1200 (in his opinion....not shared by everyone). One thing he kept using are the Polyprop caps from Wima as his output filter caps......trouble is, Wima has gone back to putting STEEL leads on the caps to save a millionth of a cent on each cap. So all the output filter caps on a Purifi module have steel leads. One of the mods I do to the Purifi module is to remove all 6 caps and dremel off the steel leads and put 6N copper leads on and then test the caps using a signal generator and scope to identify the outside foil. I mark the outside foil and then re-install the caps so the outside foil is oriented to ground. This gives noticeably better sound. No, it will not make it measure any different.

Trusting your ears is beneficial to getting great sound. Trusting the opinion of those that do not listen will just get you bitten (mosquitoes hurt!).
I well remember the Spectron Musician III and II.
The latter being better.
It was one of the first Class D amps. It also used an analog ps.
A quite large transformer. It sounded great. There were some failure issues though. And the company was a bit shady. My system at the time was miles away from what I now have. So I can’t really give a clear opinion.
The Starke Sound amp looks very interesting. Combining an analog ps should be a significant thing. But since AGD I am just not interested in any other amp. It is easy to say that the search is over!