Imhififan makes a good point about the possibility that the amp is a 100 volt model being operated with 120 volts. The voltage the amp is designed to operate with should be indicated on the rear panel.
Regarding the Kill-A-Watt meter, I have no experience with and no particular knowledge of such devices, but I wonder about what kind of accuracy it would provide when used to measure the power consumption of a power amp or integrated amp. I assume that what it does is to multiply together a measurement of voltage and a measurement of current. But are those measurements "true rms," or something else?
And if they are not true rms, given that an amp draws current mainly during a small fraction of each 60 Hz period, when the instantaneous voltage of the AC at the output of the power transformer approaches positive and negative peaks and exceeds the voltage stored on the filter capacitors by enough to cause the rectifier diodes to conduct, that would seem to raise questions about how meaningful the measurement is.
Also, given the inductive nature of the power transformer and the capacitive nature of the filter capacitors, perhaps voltage and current aren’t quite in phase with each other, which would also result in some inaccuracy if the device calculates power consumption by simply multiplying the two numbers together. With the inaccuracy being in the direction of overestimating the number of watts.
Perhaps one of those having experience with these kinds of devices can comment on these questions.
Regards,
-- Al
