Hello Ryan & Bombaywalla,
The reason I suggested making the measurement "with the component driving the amp turned on but not providing a signal" is so that in the event that all of the electronics is DC coupled, and a large DC voltage is being generated due to a fault upstream of the amp, the measurement at the amp output would pick it up. (In this case, of course, it turns out that the NAD T757 that is being used is an A/V Receiver, rather than just a power amp, so what I said would apply to whatever source component is connected to it and selected).
Assuming that the -22.6 is volts, not millivolts (and I suspect it is volts given your mention of a mild shock sensation), that is definitely abnormal and indicative of a major fault, that could conceivably burn out any speaker or Zero that is connected. However given what has been said I suspect the Zero is ok.
If you haven't already done so, the next step would be to verify that the -22.6 volts is present at the output of the NAD when nothing is connected to it, except power. If anything close to that much voltage is present under that condition, the unit needs to be professionally repaired.
Good luck. Regards,
-- Al
The reason I suggested making the measurement "with the component driving the amp turned on but not providing a signal" is so that in the event that all of the electronics is DC coupled, and a large DC voltage is being generated due to a fault upstream of the amp, the measurement at the amp output would pick it up. (In this case, of course, it turns out that the NAD T757 that is being used is an A/V Receiver, rather than just a power amp, so what I said would apply to whatever source component is connected to it and selected).
Assuming that the -22.6 is volts, not millivolts (and I suspect it is volts given your mention of a mild shock sensation), that is definitely abnormal and indicative of a major fault, that could conceivably burn out any speaker or Zero that is connected. However given what has been said I suspect the Zero is ok.
If you haven't already done so, the next step would be to verify that the -22.6 volts is present at the output of the NAD when nothing is connected to it, except power. If anything close to that much voltage is present under that condition, the unit needs to be professionally repaired.
Good luck. Regards,
-- Al