Did you buy the power supply when you bought the scanner or is it one you already had? A little over 9 volts probably won't hurt it, but if you want to be on the safe side, go to RS and buy the recommended one for your model. The more important thing is that the polarity of the plug is correct and that it has a sufficient current rating. Of course I am not going to replace your brand new $500 scanner if it fries when you plug this power supply into it, but I wouldn't think there would be a problem.
P.S. I checked the "wall wart" for my scanner. Even though it says 9VDC output, it is actually 11.14 volts and it has not let the smoke out of my scanner!
Good luck!