Jim Smith makes the really important point that initial system setup is far more effective on sound quality than tweaking and tuning.
I strongly believe that many (most) hifi enthusiasts (those who are not outright technophiles) devote too much attention to the pursuit of better sound (almost always to be achieved by upgrading, i.e. spending ever more money) instead of focusing on system setup to get the right sound. This is fueled by vendor marketing, of course.
A glaringly simple example is found in Jim Smith’s advice on speaker positioning. Almost always the gargantuanrack groaning under the fantastic weight of shiny components is in between the speakers, sometimes even touching them. Bang goes the soundstage, and hello micro-vibration and feedback! Proper location is in your hands.