Anyone used 240V-120V step down transformers?

Hi - I'm new to audiogon and was after some advice. Am thinking of buying a second hand quality amp but want to be able to use it in Asia/UK/Australia. I was looking at maybe a ML335/6 but the manufacturer will only change the voltage over for the Original owner (documents required apparently).

Has anyone tried to run a 110V-120V amp (and other equipment) using a stepdown transformer, and if so, with any success - I was thinking of buying a 2000 to 3000VA toroidal transformer. What brands/ models worked and which ones to avoid? Appreciate any help/tips you could provide.