Basically, all Levinson equipment uses jumpers to set transformer primaries which are compatible with all voltages (visible on left in a picture). However, some of the equipment has also circuitry that monitors mains frequency (a chip on the right in a picture of ML390S).
In such case, even if you set primaries properly, you will get diplay message WRONG AC with a code. Apparently, when you contact Madrigal and give them that code, they will provide you with a new code which when entered through the remote will set the microchip allowing the equipment to operate with a new mains frequency (50Hz vs. 60Hz)