FOr the time being, I'm going to assume it's voltage because the current is only to charge the capacitance up to that voltage so that the membrane is under tension.
Except that the load I am trying to drive is basically a capacitor (The electrostatic transducer), or if I look maybe an inductor-ish thing (if I also treat the transformer primary as a load), and every RC or LC filter that comes into play sort of ends up involving the L or C of the load into the filter and I'm not entirely sure how to predict what will happen.
Like a lowpass RC filter where another C is the load. THere are two Cs in paralle and I don't know how to predict if what I want to be happening on the load C will actually happen.