I have similar challenges and posted similar questions, got similar responses, here's what I have and have not tried so far -
1) Modify the crossovers - probably a good route for those with sound understanding of circuit design and comfortable working on gear, but that's not me, not yet anyway.
2) Change amps - I went to a tube amp and this helped, made a marvelous improvement in the mids (no surprise) but high end smear still there.
3) Room treatments - a never ending pursuit. Adding heavy draperies on the front wall, furniture in the corners, diffusers and/or absorbers at first reflection points on sidewalls have all helped. The draperies made a huge difference in my room, but I have a window on the front wall.
4) Speaker placement - I used the Cardas approach, then experimented with angle, ended up about 5 degree toe-in. Some report much improvement by moving the speakers to the long wall, but in my room that didn't help and made it nearly unlivable, but my room is only 11.5 feet wide.
5) Change/improve source. I have a PS Audio DSD and some suggested going to a "warmer" DAC, Mac or Bryston, but so far I have chose to stick with the PS Audio.
6) Power - upgrade everything you can in the power supply. For me, Cardas Clear M AC cord for the amp, plugged directly into wall, made a nice improvement. Listening room is already on it's own circuit, I will be trying a higher grade outlet next. Fuses maybe?
7) Isolation - improving isolation of the amp helped a surprising amount for me, so I will keep tweaking with other components too.
8) Different speakers have been recommended (I have Thiels) - well that's just silly, as I want to optimize the SQ of my current speakers.
9) Room correction components/software - kinda like the speaker crossover modifications, this is just beyond me at this point, I'd rather spend my audio dollars on other things for now.
10) Subwoofers - same as above. Someday probably, but not in the near future.
11) Cables and interconnects - I have avoided going down this rabbit hole so far.
Bottom line - there are many ways to skin this cat. The good news is that most of the things I have tried so far, while not always helping solve the treble problem, have led to other very nice improvements, like detail, resonance, and staging.
1) Modify the crossovers - probably a good route for those with sound understanding of circuit design and comfortable working on gear, but that's not me, not yet anyway.
2) Change amps - I went to a tube amp and this helped, made a marvelous improvement in the mids (no surprise) but high end smear still there.
3) Room treatments - a never ending pursuit. Adding heavy draperies on the front wall, furniture in the corners, diffusers and/or absorbers at first reflection points on sidewalls have all helped. The draperies made a huge difference in my room, but I have a window on the front wall.
4) Speaker placement - I used the Cardas approach, then experimented with angle, ended up about 5 degree toe-in. Some report much improvement by moving the speakers to the long wall, but in my room that didn't help and made it nearly unlivable, but my room is only 11.5 feet wide.
5) Change/improve source. I have a PS Audio DSD and some suggested going to a "warmer" DAC, Mac or Bryston, but so far I have chose to stick with the PS Audio.
6) Power - upgrade everything you can in the power supply. For me, Cardas Clear M AC cord for the amp, plugged directly into wall, made a nice improvement. Listening room is already on it's own circuit, I will be trying a higher grade outlet next. Fuses maybe?
7) Isolation - improving isolation of the amp helped a surprising amount for me, so I will keep tweaking with other components too.
8) Different speakers have been recommended (I have Thiels) - well that's just silly, as I want to optimize the SQ of my current speakers.
9) Room correction components/software - kinda like the speaker crossover modifications, this is just beyond me at this point, I'd rather spend my audio dollars on other things for now.
10) Subwoofers - same as above. Someday probably, but not in the near future.
11) Cables and interconnects - I have avoided going down this rabbit hole so far.
Bottom line - there are many ways to skin this cat. The good news is that most of the things I have tried so far, while not always helping solve the treble problem, have led to other very nice improvements, like detail, resonance, and staging.