And the biggest influence on sound quality is...

I see the point and can't disagree.  Once a system has good, revealing speakers, the impact of changing the front end can really change the listeners experience.  And I forgot about the recording.  Even on a mid-fi system, a poor recording or poor engineering of a recording can annihilate the music.  And the better the audio equipment, the worse that thing will sound for sure.  I guess if someone has a lousy recording of music they really like they could scout around for an old Radio Shack stereo.

Ossicle2brain +10

I have a slightly different take.  First, the best enhancement to SQ is a bong hit of some good hybrid.  Never fails!  But at this stage, having heard my classic rock a million times, I find myself listening to a lot of bootlegs, especially Led Zeppelin, my favorite rock group.  The boots vary in quality from soundboard, near commercial quality, to not so good audience tapes from the '70's.  I find that my current system makes everything sound better, i.e., well-recorded music sounds fantastic and poorly recorded music still sounds good although the difference in SQ is obvious.  So I think that some systems are so resolving that unless something is well-recorded, it sounds like crap.  I prefer a system that is smoother . . . not that detail is lost, but sounds smoother.  My ARC/Pass combo with Wilson Sabrina X speakers, an MSB DAC and a loom of Shunyata Sigma cables and Shunyata Everest, hit that sweet spot!

 the best enhancement to SQ is a bong hit

That has done some magic as far as my auditory perception goes!  

I really think it comes down to the quality of the bong.  Is it a natural bamboo bong, glass, or something makeshift?  The best SQ is always realized thru bamboo and good headphones 😂