They look to be based around ICEpower 125AXS2 modules and an input buffer will merely be a unity gain stage to modify the unit's input impedance, although I can't see a figure for this specified in the ICEPower datasheet. There's no reason to assume its any thing out of the ordinary, though, so a buffer shouldn't normally be necessary.
As an aside, neither unit appears to meet CE standards for internal wiring from what I can see, although the second one is a bit better...
Engineers: fixing problems you didn't know you had in ways you don't understand.