@mikhailark, ime a "relaxed, non-fatiguing sound" is predicted by a gently downward-sloping first-arrival sound, and an off-axis sound that has a very similar spectral balance. I’m not a big fan of deliberately introducing dippage into the 2-6 kHz region you mentioned, as that can remove some of the upper harmonic richness that draws you into the music.
Also, horns came up in the thread, and imo prosound horns (like you’d hear at a concert) are not representative of what good home audio horns can do. Most prosound horns deliberately introduce diffraction (via a sharp discontinuity in the horn itself) to improve the uniformity of their coverage pattern, but the downside is the introduction of a harshness that becomes increasingly audible and objectionable as the SPL goes up. Good home audio horns and waveguides do not have this issue, and have the advantage of reducing the spectral discrepancy between the first-arrival sound and the reflection field, which in turn is ime a contributor to long-term fatigue-free listening.
If you do find speakers in your price range that have the characteristics you want, don’t overdo it with the absorptive room treatments. If too much high frequency energy is removed from the reflection field, listening fatigue can actually be increased. This may be somewhat counter-intuitive so let me know if you’d like an explanation.
Can you give us a guesstimate of your room dimensions?
How critical is the appearance of the speakers?
Do you have a ballpark idea of the weight limitations, given that you’ll presumably have to move these by yourself?
Best of luck in your quest!
Duke