As Albert Einstein said , not everything that counts can be counted.
Technics showed a graph over 30 years ago on one of their integrated amps
and a pretty clean sign wave, vs a Airtight. Vacuum tube model . And stated Vacuum tube is now obsolete , sonicly SS equipment at the time under even a bit of distortion was gritty and bright ,where the vacuum tube rolled off with even harmonics and smoother , SS amplification has come along way in 30 years and sounds very musical , graphs are good but don’t tell the whole story ,
also your Room can play a huge part of the equation damping the room of 1st reflections ,bounce reflections ,Bass nulls treating your room should be on your short list.