I just bought one of these and it works perfectly fine with my S50 deck. Though that's for 100V converting to 120V.
I'm sure there are similar units for 230V to 100V
https://www.amazon.com/PowerBright-VC100J-Transformer-countries-Convert/dp/B00757RYPK/
about $20 on amazon for a converter, and you can use it on other things you happen to buy like those MD power supplies from japan. it's not a bad long term investment. 100 watts is fine for electronics without a heating element. hairdryers/kotatsu/bread machines and you'll need something larger. Boomboxes, AC adapters for Minidisc, and even some game consoles are ok with 100 watts.