As @jeffseight mentioned earlier in this thread, there is an excellent recent YouTube video called "The perfect power amplifier?" by Harley Lovegrove of Pearl Acoustics. Harley praises the accomplishments of Bruno Putzeys and his colleagues on building the Purifi amp modules, which are outstanding for their clarity, detail, tight bass, and dynamics. However, at the same time Harley says that the Purifi module is not all that pleasant to listen to without an excellent buffer to increase the gain of the module.
Harley mentions that Warren at VTV generously sent him a Purifi module along with a couple of op amps to use with it, one from Weiss and another from Sparkos. (He preferred the one from Sparkos.) So Harley’s view (and VTV’s too) is that the Purify module is a great starting point, but it only becomes a great amp with the right implementation. As Harley suggests, it’s technically brilliant now but it isn’t amazing yet.
In my opinion, we should applaud the efforts of talented designers at Atma-Sphere, AGD, Orchard, VTV, and elsewhere who appear to be using Class D models (whether using MOSFETs or GaNFETs) to try to make the best sounding amps possible. This may often involve more costly R&D, parts, power supplies, and custom components or modules to be successful in the marketplace.
Harley Lovegrove mentioned that he recently had the pleasure of having Bruno Putzeys come over for an afternoon of talking and listening to gear. Harley will be publishing his full interview with Bruno on March 14. It should be interesting!