From what I understand, the Spike system has a single 48 volt power supply and it feeds 48 volts to all boards. Each board has on-board voltage regulators to drop the 48 volts down to +5 and +12 for the needs of the particular board. Now if you look at what other manufacturers are doing (such as Spooky for example), they use TWO power supplies: a 48 volt one just for the coils and an additional dual output switching power supply which provides the +5 and +12 for the boards. By doing things that way, no regulators are needed on any of the boards.
The way it looks to me is that Stern is cheaping out by using one single output power supply instead of using two power supplies to power all boards.