The only reason behind Wall Warts is the difference between power supplied by various nations of the world. While in the U.S., Canada and Mexico 120 Volts A/C is the norm, this is not the case in the rest of the world. Therefore, manufacturers make the keyboards, vocal processors, etc all exactly the same. The only difference is the type of wall wart supplied with that equipment. It just makes good exconomic sense. I have not checked this out personally, but a tech friend at a local music shop said he discovered this on some of his technical bulletins.

Cheers,

Gary