Hi Mark,
I know first hand what you mean about these speakers. Live and learn for the OP I suppose.
I installed the exact setup (not my choice)
in a coffee shop near Rutgers U.
I don't know where the OP is located; but the 70V version is only available in the USA.
The back of the speaker doesn't have an exposed multi-tap. It's got two screws for 'plus' & 'minus' and the blue 'C' has a spade connector that is pushed into one of four corresponding slot 'taps' 1watt, 2, 4, 8.