4 kHz is of course the main frequency (followed by 3 kHz) that folks with noise induced hearing loss tend to lose, its commonly referred to on an audiogram as a "noise notch" because its just that, a notch in otherwise normal sensitivty across the frequency range. As some folks age, the high frequencies tend to decline as well, and when your 6 and 8 kHz + start to dip down enough, the "notch" becomes more of a slope, making it hard to tell noise exposure from things like presbycusis, aka age related hearing loss, but when I see guys in their 20's and 30's, who are musicians, active or past military, factory workers etc, and that don't use hearing protecting, 3 and 4 kHz are always declined.
Point being that if you find your raising the EQ a considerable bit in those frequencies and its sounding subjectively "good", you may just be compensating for your own hearing loss and limited audibility in that range, and others with normal hearing sensitivity probably think it sounds very harsh