Greg Covey is the marketing director or something like that of FMA Direct.

The 12amp power supply might be the best value. You can look on Ebay for the pyramid power supplies to try to find them for cheaper.

Papa,
Make sure you check with Mike to see what he can get you for a power supply.
Also, check your PM for a couple other suggestions (I refrain from posting references to other retailers).

If I want to run two 10amp chargers do I need a power supply rated at 20 amps?

At least 20 amps continuous, yes. If you're running both chargers at 10A, I'd play it safe by going with a power supply that will offer up at least 25A continuous.
Remember to make sure that the number of amps you see on the power supply is continuous and not peak. I've seen power supplies that say they are 10A, but are really 10A peak with 7A continuous.

Thank you for the power supply comments.:cool:

Seems like Gustav and Metalman were right on with the wiring in series advice.