Class H amps?

So if Class H is still analog, what is BENEFIT over A/B. Just power consumption/weight?

Yep, attempt to get to Class D efficiencies of manufacturing as well as power usage without the switching issues.

If the linear amp is kept in Class-A, then the efficiencies over a Class A are really outstanding. AFAIK, they make no claim that H is better sounding than A or A/B, but as good, with much higher efficiences.

The point made elsewhere, that it’s all in the implementation, is really important.

It may help to understand that due to FTC rules, most amplifiers have to be heavily overbuilt.  FTC rules require pre-heating at (I think) 30% of the rated power for an hour before testing for noise, distortion and output.  This is a situation never encountered in music.  If you have a 300 W amplifier, you don't play music at 100W continuously.  To meet the FTC requirements an amp must have excessively over-built heat sinks, which adds so much to manufacturing and transportation costs.  Anything that reduces the weight of an amplifier not only makes it cheaper to make, but greatly reduces the carbon footprint. 

Can an analog Class H still have (would make sense) a switched mode power supply (LOTS of weight saving right there)? 

Can an analog Class H still have (would make sense) a switched mode power supply (LOTS of weight saving right there)? 

Absolutely.  This seems to be what the NAD Hybrid amps are doing, but they have very very little information out in the public domain.

Yamaha's EEEngine amps also have this type of design. 

One engineering difficulty about Class H though is the voltage rails have to anticipate the signal peaks.  There's some interesting discussions online about Yamaha's implementation, distortion, and fixes.  Class G solves this problem by having multiple rails available all the time, but this adds to the possibility of distortion when those rails switch.

My Soundcraftsmen A400 became scary good, after removing the wimpy power cord and hotwiring a 10 ga power cable I built to replace it, and, creating a 2ndary ground. Took this amp to another level. Power cords make a difference. Anyway, having owned many Soundcraftsmen products, I kind of know the story of Paul Rolfes, who was the chief engineer at Soundcraftsmen, and happens to be credited with the development of the signal-tracking multiple-rails power supply, as well as other patented circuits, which led to his development of Class H. When MTX bought out Soundcraftsmen, it was quite soon that they shut down the line, which was imo unfortunate, as the products ( for me, specifically power amps ) were quite good. Just some history. Enjoy ! Always, MrD.

@mrdecibel what other models aside from the A400 are in that 'group' (with respect to powe and sound quality)? Does the A-5002 fall into that category?