First of all thanks for all your videos and awesome builds.

I bought a WiIlsenton 300B a year ago. I was not happy with that - usual problems with rectifiers and it sounded much worse than my diy Fistwatt Aeph J monoblocks.

Decided to convert it to your 300B build with some modification as a proof of concept.

It sounds fantastic now. I can highly recommend 6SN7 tubes from Linlai the Elite series.

Not cheap but so far the best I have had.

https://linlaiglobal.com/index.php/product/linlai-global-elite-e-6sn7-vacuum-tubes-pair-or-single/

I tried to reuse as much gear as possible. Power supply is providing only 405V B+ and with 75mA it sounds the best to my ears.

My speakers are sensitive  (107dB) with 18 Ohm impedance. I need just a little current but a lot of voltage gain. This is why I experimented with the plate load resistor of cascode.

I am right now with 56K and in my system it sounds much better than 47K. Considering to go even a little higher.

Based on my studies, 5k trafos would give me more voltage swing than 3.5k that i have now.

I still have a little 100Hz hum with the current PSU. I hope changing "middle capacitance to 560uF will fix it.

Few pics attached.

Jacek