Doug Sax had the best method of determining the transparency of any given piece of equipment---the bypass test. He would compare a live feed from his studio with the sound of the same signal passing through the device being evaluated. Any difference between the sound of the two was the component adding it’s own sound to the signal---aka distortion. The idea of high fidelity is to minimize that difference. Hi-fi components aren’t musical instruments, they reproduce them. The sound of musical instruments and voices contain timbres and textures; a hi-fi system should have none of it’s own. In fact, the less it has, the better able is it to reproduce that of instruments and voices.
It’s a very old dilemma: Do you want your system to reproduce the sound contained in recordings---whatever that sound may be, or do you want it to create sound you "like", regardless of the sound contained in recordings? J. Gordon Holt, the pioneer of subjective reviewing, argued for the former and against the latter. Harry Pearson’s standard was what he called, as we all know, the absolute sound---the sound of acoustic instruments in a real space, like a concert hall, cathedral, or even recording studio. But that construct relies upon the assumption of recordings containing such sound, waiting only for it to be reproduced. Very few recordings contain pure acoustic sound in a real space (in Pop music, virtually none do), yet Harry and his believers continue(d) to evaluate components based on their ability to create sound like that heard in those real spaces.
That is not so different from Amar Bose designing a loudspeaker that mimicked the 11% direct / 89% reflected sound heard in concert halls. That is imo an inherently flawed concept (recordings made in those spaces contain the direct and reflected sound; to play them back on the Bose 901 doubles the effect. For Bose’s concept to work, recordings would need to be made in an anechoic chamber). So imo is the notion of a hi-fi system itself being approached as a musical instrument, "tuned" to one’s liking. Minimizing the sound added by the system, on the other hand, is a noble pursuit. A hi-fi system (and perhaps I ;-) should not editorialize. The sound of the listening room is itself, of course, part of the system. Perhaps the largest part, along with the recordings. Minimizing the deleterious contributions of the listening room is imo the biggest challenge facing music listeners.
Guitarists who play in more than one tuning often have multiple guitars on stage, one (or more) for each tuning. They don’t play one guitar, retuning it for different songs. I find it hard to believe many here have any desire to re-"tune" their system for each recording they want to listen to. Am I mistaken? Don’t most of us want a system that makes ALL recordings sound as much like what we think music does (or perhaps should)?