Is it too bright or is it high resolution?

This "brightness or resolution?" question has been on my mind a  long time. When I first got interested in high end audio in the mid-1980's, I visited many high-end audio stores around the country. I was struck me how, very often the most expensive equipment was (to me) noticeably & unacceptably bright--and often was also lacking in upper bass/lower midrange content. I ultimately found very high resolution systems (preamp/amp/speakers) that weren't bright in the least, had realistic warm/impact in the bass region, yet managed to  convey all the details on LPs, FM radio, or CDs.

I am now repeating this journey in desktop audio & headphones, where many highly respected products are literally treble cannons.

My objection now, as it was then, is that elevated treble (whether in pursuit of "resolution," or just the pleasure some get from amped up treble) sounds nothing like real music. I've been in music halls, jazz clubs, and other performance spaces countless times, and barring music that's entirely electronically conveyed (which plays by different rules), the treble sounds nothing like it does on audio systems. IRL, treble from things like triangle, violins, and high notes of the piano shimmers & sparkles, but disappears quickly; while bass instruments create sound that lingers, while also impacting one's body. In actual performances, details are all simply there, as produced by musicians, with no emphasis needed in any part of the frequency range.

Only in audio equipment does elevated treble impersonate detail.

For me, with a new high resolution system, I do find that some recordings emphasize mid- to high- frequencies, more brittle sounding obviously than the actual performance live. Maybe it is the Wilson speakers.

Since I am also a neuroscientist/neurosurgeon, I would say that there is no gender difference between age-related hearing loss, unless you are referring to older men married to younger wives. I am a product of the 1960s, and went to about a dozen Jimi Hendrix concerts, and many more by Cream, the Doors, Big Brother, etc. I was recently tested by an audiologist and I have no loss of frequency across the entire range - there are significant inter-individual differences in the ability of the muscles of the inner ear to protect against volume-induced damage.

One must wonder if a "to bright"  presentation may be the result of harmonic distortion. Whether this is an amplifier issue a preamplifier issue or the interplay between the electronics and speakers. I am certain that we all want all of the details without undue brightness.
Hearing checks are not the answer.  If your system is unpleasant in the upper frequency(s) then it is time to approach your system problems in that area. Easier said than done.
For example if your speakers have metal dome tweeters then they could possibly be a source of the brightness. As others have mentioned, room acoustics and cables are certainly contributing as well.

brightness and clarity are two different things.  brightness is emphasis on the higher frequencies, and clarity is the definition between instruments, singers, etc.  When wearing sun glasses, the high frequency waves are eliminated, but (especially on the new coated lenses) definition is increased.

If it sounds good to you, isn't that all that matters? Now if your trying to get your system to sound neutral and non-bright, then your going to have to hear other well established systems along with having trusted audiophile friends help you tweak your setup.