Bringing this “Class-D GaNFET” topic back into the foreground! Found “Ask Paul’s” 5-27-23 comments about “scary new solid state designs” (1:55 mark) Tube preamp life - YouTube Very Interesting! His emotional inflection seems to indicate surprised sonic revelations that could become future SS circuit topologies! Paul, could your reference be related to the new GaNFET (vs MOSFET) amp circuit designs??? 
Ted