I just started using a 250k Ball VP Jr in front of my hd500, playing with piezo pickups. My universal input Z is set at 3.5 meg, but would that be negated by anything in front of the input? I want my setup to be as flexible as possible, so that it does not change tonally, regardless of whether I am using the volume pedal or not. Do I have to set the input Z to the same as the volume pedal's impedance? I would be putting the volume pedal in the fx loop, but a few of my patches are maxed out, as far as slots go.