The 7700 uses a pair of toroidal transformers, actually. Scroll down to the middle of this page and you can see some pictures of a 7500's internals (the 7700 is similar, just with two more amp channels inside).

As for the voltage and current requirements on the secondary side of the transformers, I haven't a clue - you'd be best off giving Outlaw a call and quizzing them on it.