davidmolliere
Headphoneus Supremus
For the A filters from 1-5, it would sequentially attenuate the mids and highs, but as they say later on: "As we move to Filter A-6 and beyond, the constraint on the mid-range becomes greater than that of the other ranges, placing emphasis on low-range and the high-range sound." Meaning it would start exponentially dip the mids and as a result increase bass and treble presence.
Did the extra bass help even out the harshness? Using the A-9 Filter actually increases the treble presence based on the charts so I'm surprised it helped reduce sibilance
I think it's not very clear in the tuning guide which filter does affect upper mids, lower treble, higher treble... and don't forget I combined this with B-3 which goes the opposite way. We'd need some kind of simulator app to really know how all this combines but what I am hearing is attenuated higher mids and more lower mids presence making for a fuller sound as well as preserved treble extension but with a warmer tone and a tad less sparkle.