any good 110v-220v voltage converters??

Albert you pronounce it cayble??? It's Gary from L.A., and I agree with Mr. Porter. Using any kind of step up/down transformer can create a sonic nightmare. Any chance that amplifier has a multiple tap primary on the power transformers? That means it is capable of being configured for 120 or 240Vac. You might want to ask the folks at Bryston.

Do you own or rent the properly this equipment will be used in?

The reason I ask, you can wire USA homes to provide 240V, it's what ovens, clothes dryers and some other appliances operate on.

Sound will be better using correct voltage without need to convert, it might even cost less to have an electrician run the wire than buying the extra piece of equipment.