Of course the immediate next consideration would be, what do I measure myself to do and equalize with absolute precision to have a flat response if then swaying my head to the rhythm of the music can make me make changes in frequency response worthy of the worst speaker design
Yeah, that's the thing, you basically can't do this above the Schroeder frequency except when the speaker has really good directivity at a given frequency.
Reflections and off-axis deviations in frequency response mean that if you EQ a single spot perfectly, another spot gets worse. Unfortunately "another spot" is closer to the first spot, the higher in frequency you go. This is the "head in a vise" phenomenon that gets talked about. If you EQ too high in frequency the "sweet spot" for listening becomes proportionally smaller.
For example, If you have any comb filtering in your room then you'll probably see more than 3dB swings with 1-2" movements depending on frequency. The wavelength of 3khz is 4.5", meaning you can have a peak and a null 2.25" from each other. So if you EQ up to 3khz then you can only move your head less than 2" from the mic position before (potentially) the EQ is totally off. It's worth mentioning here that your head is more than 2" wide.
The exception to this rule is when A) the speaker has good directivity and B) changes to the EQ are relatively broad, like 1/2 - 1 octave. So, at frequencies above ~300hz you should treat EQ more like a variable tone control.