My $.02:

The stock steppers draw about 8 amps each at idle. Geckos will output 7 amps max so you are limited to 7 amps per motor there. Standby current is 70% of that so you are looking at 4.9A MINIMUM per axis or 14.7A total. If all axes are in motion, then you are at 21 amps.

If it were me, I would get a bigger supply, something you can get from Antek, as Jeff mentioned. I didn't look at the prices, but it looks like Keling might buy their supplies from Antek (pics look almost identical), which means you might cut out the middle man by going straight to Antek. I have bought at least 5 Antek supplies and could not be happier with their quality or performance.

Matt