1. An implantable tissue stimulating prosthesis for electrically stimulate a segment of a recipient's tissue with a biphasic stimulating current signal, the prosthesis comprising: a stimulating contact adapted to be positioned adjacent the tissue segment; a reference electrode adapted to be positioned separate from the stimulating contact; and a variable bypass pathway adapted to positioned between the stimulating contact and the reference electrode, wherein the pathway has an impedance to a first polarity of the current signal that is greater than the impedance of the tissue segment, and an impedance to a second polarity of the current signal that is less than the impedance of the tissue segment.