I've discussed the Wavac HE-833 mono's with a High End Audio Engineer with over 40 years experience, and this was his take...Don't get me wrong - in turn, I really like that a small sector still-pursue making great amps, from something the size of a lighthouse bulb!
iirc c.150w for filament heater alone: daft; also, slightly splendid.
(I only need 2-3 good watts, so - not my party at all. But I can still appreciate such!)