How to measure real output power of audio amplifier. Sometimes on some cheap audio devices you can see magical numbers like 1000W or something, and device is handheld. It is not real power, it is bullshit.
Attach dummy load to audio amplifier load. The resistance of the load must be equal to resistance of your speaker. Power dissipation of your resistor must be equal to your guessed audio amp power. Set your tone generator to sine wave and frequency to about 1000Hz. Connect oscilloscope to your load. And turn your audio amplifier and audio generator volume up until you’ll see distortion in the picture.
And now time for some math.
In this example: R=4Î©, U=6V. P=1.132W
This was the power of my second tube amplifier. Audio amplifier is not fine tuned.