Another idea would be to reduce the line voltage. Look at the nameplate to see what the highest 60 Hz mains voltage rating is and then make sure the source is no more than 5/6 of that voltage.
Having said that, there is still the issue of filtering; it will have more power supply ripple. In addition, if there is a clock in the unit, it may run slow, depending on its time standard. Further, the maximum output audio power will be lower.