Power Amp..opinions please

Your post sounds llike you got plenty of opinion to put it mildy already.
"Istarted to look at ...." did you hear them as well? Class D is something you will have to hear to understand the meaning of the comments.
It may not seem constructive for people to tell you a negative criticism you say. Like class D sounds sterile and you run with it. At least you have certainly worried about it.
What kind of money are you throwing into these oversized minimonitors on a box. Mono Pass and McIntosh you have thought of Wyred4sound amps cost 3 times the cost of your 35 lb floorstanding 6.5 inch mid/woofer Quads. If you can afford big Pass or even the lighter weight Macs then you should get speakers that they were intended to play with. I had 400wpc mono I never considered using my smaller speakers with them .
I have driven my VR2s about twice that size with 2X 6.5 mid and woofer and two tweeters one a 2" mid tweeter facing backward and a 1.0 +" dome forward with a 40 watt amp. I used the amp for years with good results. Now I upgraded a whopping 20 watts to a 60 watt amp. The VR2s are 88 Db just like the 21Ls.
Yes the current amp is tubed and is more massive than both your speakers together (a DA-60) but honest it is rated at 60 watts.
Are you planning using this Quad and "could be stereo or mono block amplifier" for endless hours at earsplitting volumes or use it as reinforcement in a concert hall, arena??? A disco, PA system. If I can impart some wisdom think system not numbers. It's synergy between the elements of your acoustisphere (Copyrights retained neologism) that really is, the most critical objective, in order to make any set up sound good. These speakers aren't behemoth power hungry monster electrostats or planars. I bet your NAD sounds good but can't know from this computer.
As is oft repeated you will really only what amp sounds good to you with your stuff in your space playing your kind of music.
So you got what you asked for.
If the moderators allowed the poster to insinuate stupid responses I hope they are fair and post my stupid answer.

Yes Milpai -
I have listened extensively to Channel Islands 100 and 200 watt amplifiers which are class D. I have auditioned Bel Canto. I am unsure they are a simple class D and not a modular digital amp using ICE or similar modules for output power. I own a number of class A/B amps of relevance here. That woud be McIntosh and an ARC non class D SS Amp.
Most of my other gear is older or tubed. My speakers are JM lab Electra 936s in my main rig. Power is Opera Consonance 800 Mono blocks with 4 PP parralel 6CA7s two pairs on each side 8 total. I roll all of my tubes except in these I prefered the stock EH. I have as many as 12 pairs of speakers.
The 60 watt amp is a Jadis DA-60 hooked up to the VR2s a good one esp for a WAF rig. Which she doesnt give a ---- about.
The class D does in fact do for me what you hear has done for them. It's sonic is stunningly strong,clean, very clear, quick and transparent... for a while it amazed me . Then something happens to many class D (not ICE) owners, they get a sense that there is a critical richness of tone missing . The amps start to sound more and more lke empty, dry, shell like with no soul. As you said sterile.
They seem perfect for things like home theater where dialogue is too often muted and lost.
The A/B amp in terms of rocking your soul or tapping your toes or internalized symphonic music is highly and truly amp dependent. Some amps just smear everything into each other creating mud from a spectral. While Others maintain clear dimensional air and spaces between the elements in the music you're listening to. The tone in all cases, I find IMHO is richer and the timbre decay more pleasing in A/B or A class amps. (lets leave SET amps out for now)
The consideration of Class A is good one but almost diametrically opposed to class D. It is the heaviest richest biggest sound of all. Although sluggish vs. class D- if you want a real punchy but toneful bass you should try it. The only other issue is that the iron fisted bass can dominate the whole presentation and soundstage can be obliterated.
Since you are a devout tube hater I will only mention in passing that my 60 watt amp runs in pure class A and preserves the holographic soundstage. A good SS Class A amp with a good pre is always a delight to hear but I never had both simultaneously.
That is my honest thinking.