I associate harshness with midrange peakiness more than treble. Which is why I avoid headphones like the SR-225, W5000, and Stax SR-404.
Flats and HD414 pads helped, but they still sounded bad to me.
Which is why I really need an extended audition of the Omega 2 again now that I've heard a lot of higher end gear. From what I heard twice in the past I should really love them with where my tastes have gone. I was really tempted to buy a pair after the NYC 2006 meet, but I think I ended up getting a K1000 amp instead.