I have no dog in this hunt, no respect required. I don't usually get any anyway.
This popped up in one of my emails so I passed it on; frankly, I barely had time to skim the article.
20 W into 4 ohms is about 9 Vrms and thus 65 uV (assuming rms) is about 102 dB. Seems rather average for a power amp, yah, particularly A-weighted.
I was trying to remember the last amp kit I built (I shifted to designing my own for a while). I think it was my Hafler, and before that an Ampzilla. With Dynaco, Eico, and Heathkit sprinkled in there, somewhere, in the the primordial past.