When testing an amplifier that has a 8 ohm, 25v, & 70v output, should I be able to read either 25V AC to gnd. or 70v AC to gnd. using a multi-meter with no speakers attached? I am only reading 1-3 volts AC at the 25V pin and 3-7 volts at the 70v pin. Do the speakers with matching transformers have to be connected to correctly test this voltage?