Trying hard not to electrocute myself...
Transformers and amplifier for hifi and professional use. Kurt is an awesome guy with audio running through his veins.
DAC guru with commercial products in the digital domain, as well as some excellent tube amp modifications like heater/filament and bias supplies.
Maker of the famous Coleman regulator for directly heated filaments.
Several really nice PCBs for DIY projects like heater/B+ supplies and even complete amps.