Martin I had the exact same problem. I bought a balanced mains unit that stepped the voltage down slightly to about 220v.
That was about 3 years ago and my valve amp has operated OK at this voltage since then.
Analogue
401 / PU7 / AT33ev
Longdog Audio Quartz turntable PSU
Longdog Audio MCJ1 - Prototype Phonostage
Digital
Innuos Zen Mini Mk 3
Topping D50s
Caiman Seg & Dorado
Cambridge CXC
Amps
Tron Seven Linestage
Bel Canto Set 40 or Nick Gorham built 300B Set Monoblocks
Speakers
Tannoy GRF Memory.
Tannoy ST100.