Hi there, thanks for liking the design :)
I used one amp to drive the lot - I powered it with a regular run of the mill power adapter that's sufficiently rated for the amp. Currently I have actually removed the amp as I've got the array setup as a center speaker on my surround system in the family room. It's hooked up straight to the center channel of the surround amp. Like most surround systems the center channel is "mono" so I wired the drivers in series / parallel to get to an impedance suitable for my amp.