Suggestions for Class D amplifiers with Marantz AV7704 and B&W cdm9nt combo for HT.

Class AB is still the go-to choice? I was looking at the cabinet again - as a Class D choice is not my first choice - and I can install thermo-controlled fans in the cabinet to bring in cooler air and exhaust hot air... or I can leave the doors open during use I guess.

I don't think so, no.

I think we are well past this. Which amp and which speaker matters. My current Class D are far better than a lot of Class A/B amps, and some Class A amps I've heard, some megabucks. 
The amp / speaker integration matters a lot more than which class of amplifier.

The rest is snobbery. 
My suggestion is get a Class D amp you like the sound of, and put a portable digital thermometer there to figure out if you need anything else.

Best,
E

I still love my Wyred4sound SX-500 monos feeding Von Schweikert Speakers. Detailed with natural voices and solid bass, at least in my room. 

I am not into class D and not a fan of it. Class D amps are fine to power surround speakers or Atmos overhead ceiling speakers in a HT setup. I would never use class D amps for stereo music playbacks.
While it’s true that today current class D design amps have come a long way and have improved quite a bit compared to older class D designs from back in a day like some 10 to 15 yrs ago or older, but they are still lacking body, volume, air, midrange bloom, full mid-bass & bass power and overall musicality in comparison to very high quality analog or class A & AB designs IMO. Class D can usually sound leaner thinner lacking body and volume and somewhat analytical and lacking that lush analog sound and don’t sound liquid and fluid as good class A & AB designs. It's true that today modern class D designs have smoother highs compared to older class D designs from back in the day. 

@caphill Class D amps are also analog if I am not mistaken. 

@lightfighter2018 have you considered Hypex NC500 based amps like Nord or Apollon?.

@caphill Class D amps are also analog if I am not mistaken.

Class D amps are binary, but not digital. Weird, right?

They are not "digital" because they lack an Analog to Digital conversion stage, however, the output stage switches between on and off.  The rate at which that switching happens is controlled entirely in the analog stage.

Best,
E