Hmm, interesting question as the transformer converts alternating current (110 vs 220 volts) at some frequency (50 or 60 cycles a second) to direct current at 12, 5, and -12 volts which is constant with no variation. Now let's see, is there a way to have DC current with a frequency of 50 or 60 cycles a second. Er, No. Since the graphics chips (Agnus/Denise & Alice/Lisa) generate a PAL signal from DC current you should have no problem.
I think you you will be fine.
