Yes, A-590 and CD-32 psu have the same voltage, but I think the A-590 psu has more power. My CD-32 has a A-590 psu and runs fine with it, but a CD-32 psu migeht be too weak to power the A-590 ?!?
But unfortunately you cannot power a C64 with a A-590 or CD-32 psu ! The C64 psu has 5V= and 9V~, whereas the A-590/CD-32 psu has 5V= and 12V=, like a PC psu. There are instructions on the net how to modify a PC psu for C64, but it is rather complicated because the ~current has to be generated !