This subject comes up periodically with shoppers of Accuphase gear designed for the 100VAC Japanese market that are grey market in the USA. There are apparently aftermarket modifiers in Japan who do a 100-->120 volt conversion, but I am not sure what that does to the warranty (which is not a USA warranty and apparently no one in the U.S. agency for Accuphase will service these units.) If you haven't tried some of the other audio forum sites and Reddit for advice, you might try some local service shops. One thing I have read is that over-volting the units is not advised.
