The images shown below are InnerFidelity graphs with compensation curves superimposed. Ignore the incorrect labels in the top right corner. The green line is the diffuse-field flat speaker curve (which is the established standard for neutrality that has been followed for a long time in the headphone industry) and the black line is the Harman curve (which is a newer curve that is an average of what sound people prefer, or something to that effect). Look at the raw grey measurements and how they follow the green line. Also note that planar magnetic headphones follow the green line very closely in the bass.
First I will show you measurements for your own headphones, followed by my neutral reference, to give you better context.
Abyss AB-1266
I heard something was wrong with the Abyss unit Tyll measured, so perhaps it normally measures better than this.
STAX SR-207
This is the most neutral headphone I've seen. You could even say that it's more neutral than the much more expensive SR-009! With the SR-507 pads, that bass hump is resolved. (
click)
STAX SR-009
Sennheiser HD 800
Audeze LCD-X
Note how many of the upper frequencies are recessed.
Now that you have familiarized yourself with the way these measurements work, you can compare these headphones to others...
http://www.innerfidelity.com/headphone-data-sheet-downloads
http://www.innerfidelity.com/images/FostexTH900.pdf
http://www.innerfidelity.com/images/AKGK812SN001130.pdf