These tube DIs are inspired by the REDDI. They use a Russian Triode tube transformer coupled to the output. The output transformer was wound by CJ (at groupdiy) and is a spectacular sounding transformer. The close proximity of the power and output transformer was a challenge in this build.
Not only were the transformers mounted off-axis, shields were built to block magnetic coupling. The steel cans were mounted over the transformers, lined with adhesive backed mu-metal shielding.
The build was on turret boards in the small Hammond enclosure. I cut the boards by hand, drill the holes for the turrets on a drill press, then press in the turrets using the drill press.
DC heaters were used with a regulator and a LARGE capacitor. Physically capacitors have gotten much smaller over the past decades, making tight builds like this possible.
The level control loads the output transformer secondary as the resistance is reduced.