Many years ago, when dinosaurs still roamed the earth, I had one of these Radio Craftsmen C500 amplifiers.
5V4 rectifier, two 6SN7GTA and two KT66 in triode-strapped PP. 15 Watts RMS, response 10Hz - 50KHz.
Might be a worthy DIY project...
Two Craftsmen C500 amplifiers, up front on the two small tables:
https://www.youtube.com/watch?v=MYuepO8Rin4
/ed B in NC