What I want to know is whether other people have tried it and preferred the sound of a bit of distortion, and whether there have been any studies showing preference for some types of distortion
What’s the music EDIT, never mind, answered above, classical.
As far as studies, there a multiple studies on distortion, including how it relates to frequency response.
But first we kind of need to know what kind of distortion you are talking about, and on that we need to know at what levels you are at for each one. That would tell us if the type of “harmonic distortion” you are talking about is the same type as in these studies.
As already mentioned, distortion is used in the recording/mixing process. Distortion in this context is anything that alters the wave form. There are plugins to mimic “tube” and “tape”distortion for example. They alter the wave form in such a way to predictably tell which harmonics are altered, and by what amount in relation to the fundamental tone. Those “effects” in the right amount, at the right time, and especially on the specific instrument, involved, will generally be pleasing to most people. But in that context, it’s no different than any other effect like reverb or phase. Which is not typically going to be studied in the sense I think you mean it. Those are simply colors and hues on an artists pallet that can be used to make drums, or bass guitar, more “pleasant” sounding to most people.
Although they may exist, I don’t think you will find studies on the preferred amount of reverb, amount of phase, or amount of change in wave forms for harmonics 2-8 that is “preferable.”
I’m not sure, and why I am very interested in your post, that the THD, IMD, and other distortion tested and measured in equipment, like amps and speakers are a the same thing you are talking about. There are of course 100s of studies on the impact of distortion, and with regard to distortion in speakers, there isn’t uniform agreement in the studies how much of a factor distortion plays in preference.
I believe that software you are using was created so those that preferred the distortion of a tube amp, for example, could add it back in at the level they liked. Of course since the creator is here they can best answer that and the theory behind it. They may also know right off hand what the low distortion devices we have caused him to spend so much time to develop it, and what he found to be the preference of people. It may just be recording to recording, track to track.