Nelson Pass is the designer of the Threshold amps of the 70s and 80s. His current company Pass Labs is marketing Class A MOSFET amps closely related to his DIY designs. They have received top reviews from the audio press. He has been a regular contributor to The Audio Amateur through the 70's and is responsible for some recent Adcom power amp (and preamp?) designs.

The Adcom amps feature minimal gain stage counts, Class A input sections and drivers, International Rectifier Corp HEXFET devices, etc., all hallmarks of recent Pass design thinking. The Pass Labs amps follow similar lines but are even more minimalist and make use of some patented concepts for increasing efficiency and reducing distortions. They also feature some apparently very trick (efficient, elegant, strong, minimalist) mechanical design. Not sure if he uses his homebrew CNC equipment or outsources his mechanical fabrication.