My opinions of this headphone may sound harsh (pun intended) but I really don't think they are bad. However, and I agree with you, is that in this price range one should not have to make such compromises regarding harshness or sibilance. Now, if the T90s were priced in the $300-ish range I might actually be inclined to be more forgiving.
Also, I envy your setup. If I had any reservations about my impressions of these headphones with my equipment before, I now know that it wasn't my gear.
It really is a shame though, the detail with the T90s is extraordinary.