Some time back I got a pair of Ultrasone Hfi 780's but found them a little harsh in the top end bass was some times a little to much.
I have done some experimenting and after trying a few things they really sound amazing.
Step one replace all cables with Canare cable. The original black cable was just to thin.
I tried some different ear pads , the stock ones made my ears sweat and where very thin . The replacements actually not only brought the bass under control but opened up the sound stage a whole lot.
There is a metal plate that directs sound to different parts of the ear, by adding a little adhesive black felt it has really sweetened the mids and any sibilance vanished.
I tried a couple different pads but the ones that do the trick come from old 90's Caliphone mono head sets I got in a charity shop for next to nothing.
The difference is night and day, Still not as sweet as my Q701's but they are more dynamic and offer more low end slam.
They are now both smooth and sweet to the ears where before they where a little edgy .