For all the people with the sibilance issue, I heard it too, but this was on the defect rev3 drivers not sure how the normal ones sound.
But yeah, there is a solution for which you do not need to use the equalizer.
You can apply the paper mod:
1.Get a tissue with multiple layers.
2. Peel off one layer.
3. Check if layer is see through.
5.Tape the thin piece of paper in front of the driver and place foam on top, and reinstall the ear-pad, carefully.
This works wonders for my closed gmp 8.35D, it does not lose any detail, it just smooths out the highs very nicely. But does not affect the mids at all.
I'm planning on doing this mod on my HE-400 when I get them :)