A propper designed PSU should not show any difference when AC is rectified to DC current. If you find there are difference either your PSU are faulty, the circuit use AC or there are noice comming through your AC inlet.
Also note electrical system are not universal around the world. Many countries even has multiple system implemented as they slowly (decades) do transition from one system to another.
Another thing, hifi buffs also discuss what rocks sounds better when used for speaker wire stands. Most of the guys in that industry has an agenda, not always in y o u r b e s t interest :)
hans