voltage transformer and tube gear

I should have mentioned that transformers can have an audible hum due to internal and external factors, but espescially when overworked. One might be quiet in one spot and be noisy somewhere else. Good grounding helps. Ideally, they should be in another unoccupied room.

The GE, Q-type, step down, general purpose, single phase, isolation (Ebay keywords) tranny of mine is dead quiet, but it's epoxy potted also. A shielded unit is also preferred but that can be tough to find out.

Many transformers have a pair of primary windings. You use them in parallel for 120V, in series for 220/240. A lot of consumer gear allows this to be selected with jumpers.

Surely you need a step-down (rather than step-up) transformer to go from 220V mains to 120V appliance? If so, the PS Audio 300 has good reviews and you can also vary the frequency - I am condidering one for a CD player