High end Class D amps?

@bluorion  I recommend you google a few basics on Class D amps.  First of all, the D does not stand for digital; A, B, and C, were all already taken, so it was simply the next letter in the alphabet.  A class D amplification circuit has a different topology/operation from the others.
Simplifying a lot, you'll find that many of the amps for sale contain three basic elements, an input buffer, the amp proper, and a power supply.  There's a lot of mix and match with these three elements.  There are different kinds of input buffer, and even ones that incorporate a tube.  There are different amp modules, from Purifi, Hypex, IcePower and several others.  There are switching-mode power supplies and linear power supplies; a subset of linear power supplies is those that employ toroidal transformers.  Some makers allow you to "assemble" your own amp on their website selecting from the available alternatives.
From here it gets a lot more complicated.  There are some genuine digital amps (not that many), and the next big thing will likely be GaN amplification.  All of these terms are googleable.

My baseline was a six year old McIntosh MA-7900 which was lovely and warm, in addition to being easy on the eyes. My speakers were B&W 804Ds -- pretty mainstream... That said, I’m in a new home office and while generously proportioned, I need an amp with a much smaller footprint.

Engaging the folks at Boenicke in Basel for advice, Sven responded directly and suggested that, if patient, I could be an early adopter and trial the new P1 amp (Class D).  I’m running his W5SE+ speakers (ridiculously expensive) and sold on their standards of excellence, so I waited...

Now being a month into enjoying the setup, I’m enormously pleased. I’ll next upgrade my W5’s to Boenicke’s W8SE+ floor standers (on a swing base). The W8’s footprint in relation to the W5’s on stands is only modestly larger, but the added volume delivers what can only be heard to be believed.

https://boenicke-audio.ch/products/electronics/p1/
https://boenicke-audio.ch/products/loudspeakers/w5/
https://boenicke-audio.ch/products/loudspeakers/w8/

@twoleftears Thanks so much! I'm still trying to learn. :)

@noble100 
Thanks ! Appreciate the response..   I have the pass XA25 which gets really warm, but it’s not a room heater like the higher output XA amps can be. I’m in NC too, which is why I eventually let my BAT VK75SE monos go. I was using various class D amps during the summer months. Those were driving my Vonschweikert VR7’s. Have since moved on to some Daedalus Speakers which are 95db sensitive, but need current to come alive. The Lil pass does a good job and sounds SET like without melting the surroundings. Been a great hobby during all the home time.. 

Hello bluorion,

     It seems like you'd like thread posters to focus their attention and advice to your original OP subject.  Which I believe is that you're curious about whether your overall system sound quality and performance would improve by utilizing a good quality and high powered class D amp, or pair of monoblocks while using your Luxman integrated's preamp section.  Here's my take:

   In my experience and in general, high quality class D amps have a very neutral and detailed presentation, like the audio ideal of a 'straight wire with gain'.  I believe this is mainly due to their inherent very low distortion levels, very low noise floors and voicing decisions made by the amp's designers, for example Bruno Putzeys,  I think other high quality class D amp module desingners have followed Putzeys lead in prioritizing accuracy in their designs.
     Some prefer this very neutral and accurate quality while others prefer a bit or more of coloration in their overall system sound.  Audio enthusiasts have various terms for these preferred colorations, such as 'warmth' or bloom', but they all typically require the amp design to emphasize even ordered harmonics, which humans perceive as euphonic, and attenuate odd ordered harmonics, which humans perceive as not euphonic, in their designs   It's also important to note that music itself can have varying degrees of euphonic qualities that we perceive.  And that the accuracy or quality of the music recording/mixing process can also either enhance or detract from the music's inherent euphonic qualities we perceive.  
     Personally, I've discovered it's best to view overall system sound as a continuum from very accurate and neutral to not accurate and colored.  I believe it's important to actually audition and experience different systems along this continuum to gain a better understanding of the differences in overall system sound qualities possible and which you prefer.
     I apologize for the length of this post but I know, from a lifetime of personal experience, that finding and creating an overall system sound quality that you really enjoy is complex and full of subtle shades of gray in practice.  I make no claims of simplicity in my journey or your possible journey.
    Nevertheless, I do have a few suggestions that are likely to shorten and simplify your pursuit:
  It's an asset to be adventurous and to not be overly hesitant to try new or different technologies, ideas or things in general.
     I know I learn and understand best through personal experience, perhaps you do, too.  Trying new and different things are a good way to not only discover what you like and enjoy, but also what you don't like and enjoy. A good example is your idea of combining the high quality preamp section of your Luxman integrated with a high powered and high quality class D stereo amp or pair of monoblocks.
     From your earlier posted list, I would recommend you begin your journey by trying either a D-Sonic stereo amp (starting at $1,475) or pair of monoblocks (starting at $2,250/pair).  I suggest you call the owner, Dennis Deacon, describe your idea and ask for his advice.  He's a good guy, very knowledgeable and honest.  I know his M3 amps are very good, with very detailed but smooth midrange and treble performance, because I own the M3-600-M monoblocks.   He told me the newer M3a amps are even better but I appreciated his honesty in also stating the improvement over mine were subtle and probably not worth the expense of upgrading.
     He offers a 30 day free-in home audition period with a no questions asked return policy, so there's literally no financial risk.  I have no association with D-Sonic, I'm just a big fan.
     Lastly, I want to mention that the quality and audible sonic characteristics of the preamp utilized with good quality class D amps is extremely important because these qualities are the major determinants of the overall sound quality perceived, since the D-Sonic amps are just going to faithfully amplify the inputted signals without adding or subtracting anything perceptible.
     I can relate the very different overall sound quality presentations resulting from the different preamps I've utilized in my system with the D-Sonic monoblocks, ranging from a VTL 2.5L with NOS Mullard tubes swapped out to a few other solid state preamps, if you'd like.

Best wishes,
    Tim