Anyone use 100v or 220v gear with a transformer?

Electrically it'll work. Sonically it will not. I can't beleive nobody hears the degradation using a step up/down transformer causes. Its not subtle. I'd try to find a 120v unit instead.

Your power company uses step down transformers themselves. I use a tranformer with my Japanese laserdisc player which is 100v and have not had a problem in the five or six years I have used it. It sounds wonderful by the way. It really makes DVDs sound anemic in general.

A transformer is best when it doesn't approach it's limits. For that reason, I suggest using at least double the draw. So I agree that 500 VA to 1 KVA would be better.

Also, a transformer can have a mechanical hum, espescially when overworked or supplied dirty power. The benefits of a transformer are elimination of DC offset and roughly 12 dB noise reduction (toroids being half that but less likely to hum and more compact). Good for ground loops too. There is some draw at idle but they are efficient enough to not worry about leaving powered.

Signal Transformers has a DU series that is shielded, Q-rated and steps down to 104V. These are not in boxes and do not include plugs.

I have never experienced any drawback using power transformers aside from one (of several) humming but that one was scavenged from industrial equipment. I have used them for isolation and to convert to balanced AC and in all cases, the sound was improved. Sometimes subtle, sometimes amazing.

As usual bad advice reigns supreme. Not that I think anyone here is purposely being misleading... they just must not be capable of hearing it. I suppose that makes them lucky. Regardless- a transformer will absolutely diminish performance. But 117v gear for a 117v country.

+++ If the maximum draw of the amplifier is 195 watts, how will providing 1000 watts be more beneficial than providing 500 watts (or more than double the maximum draw of the appliance)? +++

Easy, transformers are reactive by nature and distortion/reactance goes up the closer a trans get to its rated output. The bigger the trans the better. A 1 to 5 ratio will yield about the best performance per buck.

If you were running a 200watt heater or refrigerator I'd say use a 300watt trans. A 300watt (or 500watt) trans will not let your amp do its best. .

Regards
Paul