Sorry for the necro. Just wanted to share. Maybe I could get some tips from those who own the esw9.
I've owned these babies for more than a week now. Burned it in for approx. 24 hours with pink noise, high/low frequency sweeps. To my ears though I don't find them that smooth. I actually find myself, unintentionally, reaching for the dt1350 more since sometimes I find the hi-hats and snares on the esw9 a little detached from the music, distracting if I may.
Don't get me wrong, I like 'em (except for the fact that mine had blemishes on the cups when they arrived from weemall

-irks me). I like the bass and the lovely vocals (especially with Adele's albums). But again with songs that have copious amounts of hi-hats, crashes, splashes, they remind me of my HD650 with a cardas cable - a combo I did not like.
So, does the esw9 need more burn-in time before they fully smoothen out? Is there an optimal positioning for these babies?