freeseb,
I'm almost sure that your leds don't need more than 5v.
The current would be the only thing to consider.
I'll post very soon my last schematic.
A thing to consider too:
do you use a led driver?
often (everytime) the led driver creates a cycle.
at a time T, only one led is ON and cyclically, the whole row or columns (if you decide to create a row or a column), I mean the whole group is cycling...
thus, at a time T, only one led consumes power ... it reduces a lot the current rate needed !!
but, be patient, all my project will be published (you can read my website now: http://www.julienbayle.net/diy/LiveInterface/
the reason: I'm waiting for my PCB from 4PCB.com ... and I'm in France ... it will arrive soon I hope
and after that : video, photo, schematic 
cheers