@lewm don’t forget that you stepdown from 110/117 to 100v, but i must stepdown from 220/240 to 100v like everyone in Europe.
From what i’ve read the stepdown device must be at least 3 times higher in wattage compared to the actual source (turntable). For the amps the power of stepdown trans definitely must be much higher as far as i know.
I have no problem with mine, each one is 1000w, but as i said i use just one trans for everything japanese and another trans for everything american. I can connect 2-5 devices to each stepdown trans.
I’ve been using a cheap 30w max "super" stepdown autoformer before (it looks like power adapter), but the price for those chinese stepdown devices was nearly the same compared to 10-20 times more powerful local made autoformers people using here for japanese and american audio electronics. So i went for the powerful, the equal autoformers made in USA cost $500 (local made cost under $100).
Japanese stepdown devices like
Toyozumi CD240 (or KD1000) are also autoformers and cost 3 times higher. They are very popular here.
But seems like real transformer with galvanic isolation is always better for critical audio devices, especially for amps. And safer for the user.
P.S. I know nothing about technical aspect of the step down transformers and about impact on the audio, i believe it is far more important for the amps than for the turntables. I'd like to have one stepdown for everything (universal), not many different stepdown devices.