The seating seems to make a very large difference.
I orignally was using a chair from Plummer's (a cheaper knockoff of the Ekornes style), but I found that some of the internal springs buzzed during loud bass passages. Then I moved to a leather sofa with the back around mid-ear level. I used a thin blanket over the back and found it helped cut out some excessive sibillance. I recently tried a thick comforter, and it helped further. I then moved the sofa off to the side of the room and tried a cloth office chair (the back was well below ear level)--- and WOW! what an improvement on the clarity of the treble! This won't be my long-term chair, but now I am looking for a chair or sofa with a low back, made of cloth with some decent padding. My cable dealer heard the story and thought there had been comb filtering going on.
I orignally was using a chair from Plummer's (a cheaper knockoff of the Ekornes style), but I found that some of the internal springs buzzed during loud bass passages. Then I moved to a leather sofa with the back around mid-ear level. I used a thin blanket over the back and found it helped cut out some excessive sibillance. I recently tried a thick comforter, and it helped further. I then moved the sofa off to the side of the room and tried a cloth office chair (the back was well below ear level)--- and WOW! what an improvement on the clarity of the treble! This won't be my long-term chair, but now I am looking for a chair or sofa with a low back, made of cloth with some decent padding. My cable dealer heard the story and thought there had been comb filtering going on.