Null testing why isn’t it done more in audio reviews or would the results be too unpalatable ?2

[Atmasphere]

There have been some weighted harmonic distortion schemes, ex here of HI-2 weighted distortion:

https://www.klippel.de/fileadmin/klippel/Files/Know_How/Application_Notes/AN_07_Weighted_Harmonic_Distortion_(HI-2).pdf

Nice- now that has to be happening for amps, preamps and sources, and going up to the 17th harmonic or so since there's bass