Thanks for sharing this. I just downloaded the demo to try with the various headphone models I have available.
In my quick review, Sonarworks is most noticeable on my Sony 7506's - and IMHO, quite the improvement.
It tones down the highs, brings up the bass and really seems to balance these out.
I'm not sure if I really "NEED" this plugin, but it does seem to work as advertised.