1. Make a dummy load (set of resistors) joined together the way that you get 8 (or 4) ohms total. Remember how to add resistances correctly! I used 5 resistors of 10 ohms / 10 Watts to create dummy load capable of 50 Watts 8 Ohms. Three paralell, two paralell and the whole set (3&2) in serial. Serial simply adds resistances, paralell adds inverted resistances ie 1/Ra+1/Rb+1/Rc where a,b,c are separate resistors. Remember to take care of power handling and possibly resistors cooling. You will damage 10W resistor quite soon by hooking it up to average stereo amp for more than couple of seconds. You may burn your table as well
2. Hook up a sine wave generator, set it around 50 hz (there are some online java ones). Standard ratings are made usually at 1 khz but this is what we have to compromise. Cheap multimeters work with alternating current that is standard in our power outlets (ie 50 Hz) and they do not at any other (not telling you so!) They will read some results but nowere near reality 3. Drive your amplifier input properly (volume to the max in every place responsible for volume control in your PC). Check with headphones if you do not overdrive (distort) the output 4. Hook up your dummy load 5. Swith on your amp. Drive it to the max (under the level it distorts). Unfortunately there is no way to detect distortion without oscillocope here. So by the rule of thumb use 80% of the volume rocker (unless you are sure 100% does not distort) 6. Measure AC voltage at amp …
