When I get my hands on a pair, I'm going to pitch them against everything I can lay my hands on, from dollar store earbuds to $7000 electrostatic loudspeakers. I'm assembling the playlist now, and it is VERY demanding.
So far:
Ravel's Bolero (The piece is played from ppp to fff and is incredibly complex considering the simplicity of the theme)
Rush - YYZ (There is a cymbal crash whose aftershock gets lost on all but top quality equipment)
Tchaikovsky 1812 (The version with real cannons)
Sarah Brightman and Alessandro Safina - Canto Della Terra (Female voices are extremely taxing on equipment)