Question, please... I know the consensus on here is it is ok to use a step down transformer (for Japanese amps 100 volts to be used in the USA 120 volts). But what about the frequency indifferences? I read where those can not be converted in a transformer. I read where a transformer can support both 50hz and 60 hz but will not convert them. Would the unconverter freq. difference effect the sound quality of a Class A japanese amp?