If these are Jim Thiel era- Thiels, then I'm quite sure what the problem is. Your hearing is far too good for your age. You either have to get an excessively warm/mellow DAC's like the ARC DAC 8, more neutral speakers like modern Monitor Audio, or a digital EQ to tone down the treble. For YOU and YOUR symptoms, stay away from B&W/Golden Ear or Triangle. I'm not sure how much of the Thiel sound is on-axis. With some speakers reducing toe-in can realy diminish the top octave glare.
A good inexpensive compromise if you absolutely love your speakers on vinyl is the $170 miniDSP nano. It will sit before your DAC and let you apply very subtle and versatile EQ.
https://www.minidsp.com/products/minidsp-in-a-box/nanodigi-2x8-b
Another approach is to add more room treatment which will reduce the treble output, if you don't already have it. This is always a good choice, contact GIK Acoustics, as the acoustic treatments will outlast your gear. :)
Best,
Erik
A good inexpensive compromise if you absolutely love your speakers on vinyl is the $170 miniDSP nano. It will sit before your DAC and let you apply very subtle and versatile EQ.
https://www.minidsp.com/products/minidsp-in-a-box/nanodigi-2x8-b
Another approach is to add more room treatment which will reduce the treble output, if you don't already have it. This is always a good choice, contact GIK Acoustics, as the acoustic treatments will outlast your gear. :)
Best,
Erik