It's not so much the volts that matter, a range from 6vdc to 12vdc should power it, it's the amps that you need to look out for. I wouldn't use a psu over 1.2 amp (1200 ma)
But the most common issue not usually tackled is tip polarity, most modern devices now have diodes to protect against using the wrong tip/ground set up. Does the arturia keyboards have this info on the back of the keyboard? Ie -tip or +tip
Stuart