Wow, hopefully you haven't been waiting 7 years for the answer! I'm actually using only a 1-Amp power adapter, and it should work okay, although I don't recommend anyone go below that. If the keyboard draws more power than the adapter can supply, it will get hot and be at worst, a fire hazard.
I love my CF8...it's been beat up, but the action is outstanding, and with aftertouch and 8 control knobs, it kicks a$$.