Time to upgrade my pre-amplifier (again) and is perfect timing to go back to 4P1L. The Siberian preamp had a fantastic bass response and detail.
Here is the new filament raw supply. It has split bobbin transformers, schottky rectifier bridge and input choke LC filter stage. It also has a CM choke and EPCOS electrolytic capacitors:
Power supply ready
Input chokes
Chokes and capacitor bank
Schottky Rectifier Bridge plus snubber
Building the power supply
Dead quiet at 16V output and 550mA which is the load used by 4P1L starved filaments in parallel with filament bias.
Soon to build the preamp!