I downloaded PSUDUD and got stuck when it did not list the HER208 under diodes.
Have you tested this little guy:
12V to 220V Step UP Power Module 35W DC-AC Boost Inverter Module Dual Channel | eBay
This guy did:
Royer Oscillator Inverter with Output Capacitive Dropper - YouTube
Playing with: 12V DC to 220V AC Inverter Royer Oscillator - YouTube
I've been looking for that listing. Thanks for that. I bought a few several years ago... It's good for running Nixies. Never tried a preamp with it. It's cheap though. All the cores are loose and I think the MOSFETs would melt if you asked it for 35W.