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!
In my listening room, I started with a NAD M12 pre amp/NAD M22v2 amp combo and Tannoy DC8TI speakers.  It took me a while to get the gain setting right, but once I did the sound was nice. The bass was great, mid range was good, but, depending on recording, it was sometimes too bright and not as musical as I would have liked. 

I replaced the M12 with a Herron pre amp, Herron phono pre, and Audio Mirror Tubdour SE DAC (very nice DAC!).  That combination took the SQ to another level - everything sounded so much better.  Not being satisfied, I sold the Herron and AM gear and bought a PS Audio BHK pre amp, DirectStream DAC, and Stellar phono pre. There was a clear SQ improvement - everything sounded so much better.  Not being satisfied, I bought a PS Audio BHK 250 amp.  Now I'm satisfied. 

I still have the M22v2 as my backup listening room amp, and plan to use it with a PS Audio Stellar Cell Gain DAC in another system.  The M22v2 sounds really nice in my main system, but it is not a musical or smooth as the BHK 250.  I could live with the M22 if I had too, I'm happy that I don't.
I enjoyed my time with later Nuforce/Nuprime designs. They sounded much more natural and liquid than the several other Class D that I tried. Worked well with Tubed pre amp. You do have to select Power cord and power conditioner carefully so noise is not reintroduced into rest of system.
For the 9,999th time:
  • Class D frequency response is determined by the load
  • A particular amp can sound quite fine with one speaker
  • The same amp can sound quite poor with a different speaker
ALL specific recommendations are worthless.

@bondmanp , the HS-500 Arion has a vacuum tube stage linked to the Class D.  I love it!  Never heard of them making amps.  How much is the cost?