Most filters on dacs are very very very subtle....almost a waste of circuitry and time and effort for me....if you can REALLY hear real discernible differences then YOU ARE A RARE person...congrats to you!
But for most of us mere mortals...its a dont care....really...
I just let my cousin borrow a set of Hifiman Ananda to allow him to hear a "quality" set of planar HPs. He's never heard a planar but I don't know if he'll actually "get" their SQ since they are not bass heavy, muffled, consumer cans. I agree that most
regular folks don't care about stuff like this. But when one spends $$$$ (4 figures, or more) on a good HP and/or 2-ch setup, most would want to set up their components to maximize their investments and attain the best sound possible for the dollars invested. It may be a waste of time to
optimally set up a DAC if I am listening to low-rez HPs, amps, and sources/files...but I've invested about ~$3,000 in my HP setup (over time) - between
one set of primary high-end cans, my source chain, and it's associated equipment. In this instance,
to not take the time to see which settings are best for my gear, my ears, and my tastes would be a
more massive waste of both
time and
money. For the first time in a long time my setup is revealing enough to discern the differences in a DAC's LP filters and internal settings, op amps, Hi-Rez files, recording quality, and even some cables (cheap SPC vs OFC) - without feeling that I
need or want to modify or upgrade anything at all. I'm still stoked when I listen to my music through my setup - a job well done while still being
relatively budget conscience. YMMV.