Repurposed Bogen CHB100

[Tom Phillips]

... A 7868 with those voltages should be around 44 watts per pair, but this was only giving me 55 watts with a true RMS meter, though I was measuring that on the scope with the signal completely clean. Since RMS is supposed to be with 5% distortion, then it is likely a bit higher power than that...Greg

Hi Greg,
I assume there is a typo in your post since the "only giving me 55 watts" is higher than you expected rather than lower. Regarding measuring RMS power, the manufacturer can choose any distortion level at which to specify the RMS output power of their product. A high end HiFi  amp may be measured at a very low distortion level such as 0.01%THD or less. It is pretty common for musical instrument amp manufacturers to use 5% or more and there is a lot of fudging the specs by many companies. Your True RMS meter will even correctly measure the RMS power of a fully clipped square waveform.
Hope my explanation makes sense.
Cheers,
Tom