There was a company called DAK in the 80's that sold all sorts of interesting stuff and I still use my BSR EQ-3000 which is an equalizer with a spectrum analyzer display fed by a microphone that you walk around the room with to confirm your settings. It even has a pink noise button that injects that into the amp so you have a uniform pattern to equalize. Sort of like an analog Sonos Trueplay I guess. We could do all of this in the 80s :-)