Quote Originally Posted by SuperShark
First off, I would like to say, that from what I know, the power adaptors should act as your step-downs for ya. Videogame systems run on very low voltages, like below 20V, all around the world while the outlets they plug into spit out between 100V and 250V or so (various points around the world), so the adaptors act as your step-downs.
Technically you are correct. By the very definition, something that takes, for example, 110V and turns it into 9V is a step-down transformer.

However, in the context of worldly electronics, a step-down (or step-up) transformer is a device that converts global voltage standards.

A lot of devices now use power adapters with 100-240V inputs. ONLY THOSE are safe to plug in "worldly" without a step-up/down transformer.

Plugging a plain-old 110V adapter into a 220V outlet will probably make fire. Plugging a 220V adapter into a 110V outlet will underpower the device and still maybe break something.