I wonder if makers of ham radio focused products are likely to be more economical. Tube
audio has some cult aspects to it, and may have pricing to match. (Monster Cable comes to
mind as an analogous case.)
Regulation is typically effected by a high voltage
N-fet or similar device see e.g.
-
https://www.microchip.com/en-us/product/lnd150# etc etc
-
https://www.ti.com/lit/pdf/snva020 etc etc
Yes, that works if you need regulated power. You can also use tubes to regulate (see the
1967 Handbook on
archive.org). That assumes regulation is even needed, which is not often
the case for tube circuits. Also, a simple shunt regulator is often adequate, either a
classic neon tube or a Zener diode (or a couple in series if you need a higher voltage).
I haven't worked with tube computer or logic circuits, but tube circuits in
transmitters or receivers are not normally regulated, with the exception of LC
oscillators. For those, a typical design would just use a neon tube shunt regulator.
paul