i have no well grounded opinion on how ’warmth’ is created and delivered in audio reproduction equipment, my comment below was only on the sound of a lovely live musical performance, in a good venue
on the subject of added warmth in hifi gear, i am hardly an expert at a technical level but it seems to me that skillfully rolling off some treble frequencies and boosting midrange or midbass can provide a sense of perceived warmth, relative to a true flat response... of course playing with various distortion harmonics can do the same, but perhaps to a slightly different perceived effect
the elephant in the room here is what subtractive effects result from the recording mastering mixing processes? i believe that these effects can lead to the music itself sounding lean and/or stripped of some of its harmonic richness, so perhaps components that do add back some warmth have a useful role in this (common) case...
analogy i think of is fresh caught salmon tastes a certain way, but then you freeze it, thaw it, you then prepare it... it is just not the same... so skilled chefs add something back to make the taste real nice again... even if its not the same as the true ’og’... i do feel that the commission of great hifi gear deals with this reality in the recorded material we are often listening to