9V AC is what you want for MB-6582 Rosch, since its a bridge rectified circuit,
9VDC will not work properly with a rectified circuit.
Its designed to convert AC into DC, so passing DC into this circuit will have a different effect.
"PSU Option C: People could generate 5v from a single unregulated 9v AC supply."
For the gurus:
From the wiki you get the impression you MUST use Option C if you're not using a c64 psu.
Why cant you just use Option A with a 9V AC Adapter, that has a 7 Pin DIN Connector soldered to it?
EDIT: Option A uses the 5V DC rail of the C64 PSU also, (as patiently explained by Flemming in the chat. :thumbsup: )
P.S nils and smash said that a 1A rated PSU is more than adequate.