Which Class D Amplifier? PS Audio, Ghent, Nord, Merrill or other???

Tossing arguably superior circuits or eval boards into a box will not likely make for a superior product providing a lasting satisfaction. Designers care about circuit board layout, trying to minimize circuit trace paths from RFI and noise perspectives. And then there are the vibration control and global noise/RFI isolation and reduction issues that come into play.

Thanks for the insight MG,

Nord was offering an upgrade billet chassis (I think for the NCore only), but it’s no longer posted as an option

I read another review citing power cord sensitivity. I changed one out and did get a substantial overall more organic presentation.

Based on that, last night I swapped out a Surfer Cable XLR (silver; a very good value @ $150), but when I replaced it with a PS Audio copper XLR (not sure which model, but I own it) it took about an hour to saturate, before the music refocused. Tonal tilt now favors of the midrange/base, and a lot more fuzz on the peach. It’s the kind of improvement I would expect if I can ever find a Audio Alchemy PS 5, outboard power supply for my AA Dac/Pre

Hello tweak1,

      It seems you've discovered another benefit of class D amps that I don't think has been mentioned thus far in this thread: good examples of class D amps are basically a 'straight wire with gain ', which is numerous experts' definition of an ideal amp.
     Distortion and the noise floor are measurably so extremely low that it results in nothing being added or subtracted from the inputted signal. This causes the overall presentation to be very detailed and neutral.
      The benefit of these qualities is that it allows users to much more easily discern the affects of different power cords, interconnects and spkr wires on your system's overall sound. With my prior good quality class AB amps (Adcom, McCormack and Aragon) I thought I could discern subtle differences but, in retrospect, there may have been some placebo effect occurring.  With the good quality class D amps, the subtle differences were discerned much more easily.
     On a larger scale, the clarity and honesty of good class D amps will also allow you to much more easily discern weak links in your system such as upstream components and source recordings. 
      I had always thought I preferred a warm overall system sound.  For about 5 years previously, I used a tube preamp (VTL 2.5 with NOS Mullard tubes swapped in) paired with solid-state amps to achieve this warmth.  After comparing the overall sound with and without the tubes, however, I found most of my favorite recorded source music sounded just as sweet to me without the tubes.  So I sold my VTL and a set of 4 just purchased NOS Mullards to a good friend and have not regretted it since.
     This same clarity and honesty also applies to recorded music sources.  There's no masking or coloring of the signal so recordings that sounded good to on previous amps may not sound as good using good class D amps.  The recordings are just faithfully reproduced with warts and all.  Bad recordings will sound like it and good recordings will sound especially good, the differences being obvious,
     .I discovered my CD collection consisted of mainly good recordings with just a few clunkers (for some reason my Cold Play CDs sounded much worse but still good in my car system). 
     Just after swapping out my class AB amps for class D, I also added a computer audio setup; consisting of my laptop running JRiver Media Center, a Synology NAS and using my Oppo 105 as a DAC/Player.  I ripped my entire CD collection to the NAS and began downloading some high resolution 24 Bit/96KHz music files ,too. 
     All the CDs sound very good but the music recorded direct to hi-res 24/96 sounds incredibly good; by a wide margin the best I've ever heard on my system with solid/stable 3D sound stage and the large dynamics I only previously experienced with live music.
     My main cautionary message is that class D amps may not suit everyone's  tastes or system.  For example, those that don't have the funds to upgrade upstream components that may suddenly sound deficient.  Or those who prefer a more colored system sound and don't want a very detailed presentation that will reveal the true quality of all of your recordings.  
     However, users of good class D amps are still able to tailor the sound of their system sound via the choice of preamp used.  The amp will just faithfully amplify the outputted preamp signal so it's critical that the preamp outputs the desired sound qualities.  

Hope this helped a bit,
  Tim
     
     

Looks like GaN is starting to take off.
Not only Texas Instruments (Burr Brown) who are into the manufacturer of GaN transistor technology, but it seems Analog devices now also.
  
GaN is already being developed into Class-D audio by a few amp manufacturers now, with great feedback on it's sound, compared to the older technology.

Analog Devices getting into the manufacture of the GaN technology also
  https://www.analog.com/en/applications/technology/gan.html

Cheers George  

GaN-FET manufacturers will be important to the implementation of the GaN tech in Class D audio amplifiers. And yes, wide spread availability of the GaN-FET’s will be needed to drive costs down. But GaN-FET modules designed for Microwave and RF applications will not benefit HEA class D applications. Just saying...