You can run, 50hz transformers on 60hz. If it effects the the DC power supply I can't say. It would seem to me that at 60hz there would be more rectified full wave ripples for a given time line. Filtered Dc output should be smoother, cleaner. Maybe an EE can shed some light on the subject.
http://sound.westhost.com/xfmr.htm#7-noise
http://sound.westhost.com/xfmr.htm#7-noise