Wish I had that talent.I build my own amplifiers and since I'm stuck at home I've rebuilt my system. The amplifier is now a 300b SE with a 4P1L driver in triode, amorphous core plate choke. All directly heated. I needed a bit more gain and the best way I found was to put a NE5532 op-amp board after my AK4490 DAC. The op-amps are almost transparent so the sound is determined by the tube stages, which is exactly what I want. Good upgrade.
It all started when I was a gigging bass player and my tube amp had problems! I taught myself to rebuild it and went on from there. Had to do a lot of reading to understand it all. I love building stuff. All the Meccano and Airfix models I had as a kid....Wish I had that talent.