IMO sibilance occurs at the extreme ends of the audio chain. Not your DAC or Amp. Most likely it's at the source (recorded). I think one has to have nasty headphones or IEMs to create it when it's not there in the source. I'll bet that none of you guys own nasty cans, or else they've been quickly relocated to the drawer of forgotten headphones, never to be heard from again.
Headphones that have some peak in the treble that sibilance lives in can emphasize what's recorded.
Some folks will blame amps and DACs, I think that's misplaced.