I just replied over in the Tubes forum. We must have been typing at the same time.

Off the top of my head, I'm thinking I'd go with a simple power supply circuit, bridge rectified if I could use four diodes and if not, go with a pair of diodes instead. I'd probably use an LCL filter on the output so the only the hurdle to overcome is finding caps that have high enough voltage breakdown rating.

One thing I've thought about and that I'd like to investigate is the use of 78xx or 79xx regulators for filament supplies. On one hand, it's nice to remove all semiconductors and be old school. On the other hand, it seems like the regulator might really decrease hum. Just a thought; What do you think?

Wayne