The market for high end stereo is huge in places like Japan where they no doubt have different electrical systems than we do. Manufacturers might creat standards that can be applied regardless of system. Maybe that has something to do with it.
My experience in Pro audio here (in the states) shows me it is common to utilize ground lifts to get rid of buzzing. Trying to use audio gear in old buildings with gounding problems is dificult, and it is just easier to use ground lifts than to fix the electrical systems.
Not the best choice, to be sure.
Radar
