Distortion will be Detraction.
The conundrum is the broadness’ of individuals expressing sensitivities/bias to the impression made from the detected presence of the colouration that can generate.
The are many many electronic devices that are measured to have no seen distortion in the shape of the signal or the shape of the sound curve. The Waveform is as expected for Audio Equipment purposes.
With such equipment in use, there will be listeners who’s sensitivities/bias that is detecting a detractor. Individuals who are living a proportion of their lives being entertained through the use of audio equipment, generally keep close to them equipment that is in their assessment not classed as having noticeable detractors.
In relation to the frequencies that trigger the bias, it is each to their own on this matter.
I know through the explanation of the OP, I would find great contentment listening to my Chicago Blues Artists through their set up, as I deliberately add colour to my own system for these periods set aside for listening to this genre.
Alternatively it is this colour added, that is the one that has the Amygdala produce the chemical reactions that seem most rewarding, especially when present in conjunction with recollected experiences.
Math is everything, it explains much, but for most, is a subject not interrogated to be understood, it is entity that is present and trusted.
The Math in Electronics/Physics is only one element to the equation, there is also the Math belonging to the Chemistry in the Human that has equal importance.
Multi Trillions of Chemical Reactions occur within a Human Body daily, of which how many trillions relate to being in a particular environment and having a reaction to it will be a unknown.
It will be a very weak case to suggest there is a single math formula, especially relating to Electronics Math Equation, that is the correct approach to be produce individuals that are equally stimulated by the end product.
It is the variety of Electronic/Physical Math that is to be encountered and is also required to influence harmoniously with the uniqueness of the Biomathematics taking place in each individual.
Forums do have a element of discussion, where an individual shares with a context, that is suggesting their way is without doubt the better path chosen.
This narrow field of view seemingly completely overlooks the uniqueness of each individual and how they relate to sound on a particular environment, especially sound produced in a unique space as a result of using an audio system.