This is my first hack on my new digital piano. Actually, not on the piano itself (!) but on its power adapter. This power adapter is quite big and quite heavy. I didn't like very much to hang it one the socket on the wall. It seemed to me either the socket or the power adapter itself could shortly get damaged (it happened to me with a small and light power adapter...).
So my simple hack was to add a short extension, to let the power adapter lay on the floor, using a classical plug to interact by design with the socket on the wall (BTW it is possible to add a switch on the extension, but I prefer to completely unplug the load when I don't need it).