Hear them to believe them. Amazing. The circuit for these is a 6SJ7 loctal pentode driving a 6BL7 which is directly coupled to the grid of the 805A output tube. The extra triode in the 6BL7 bottle is used as a series regulator for the second stage of the amplifier. The 6BL7 directly coupled driver is choke loaded and adjustable positive grid bias is applied to its grid to help set the bias for the output stage. The filament of the 805 is heated by a Meanwell LRS-75-12 which provides current limited warm up and relatively quiet DC power. Because the B+ voltage is so high and the 805A doesn't draw a ton of current until the entire circuit warms up, I used a series string of neon bulbs to pull the plate of the 6SJ7 down to a respectable voltage at startup to be kind to the tube itself and the coupling cap. The power supply uses a solid state voltage doubler and a CLC filter configuration. The second cap is a polypropylene defibrillator capacitor.  The output transformers are the venerable Monolith S-17. 

Power output is 32W at 10% THD 1kHz, and down to 29W at 35Hz.  Bandwidth is -1dB at 22Hz and flat well past 20kHz. Gain is around 20dB.