That's quite a claim - bass like your M50. What equipment do you plug your M50 and AD700 into?
Honestly, lack of bass can be EASILY solved by using a Graphic/Parametric EQ. Right now I'm using Play on OS X with the AU Graphic EQ plugin that I've adjusted (31 bands) for added bass, and a slight bit of super-high treble. They sound like my ATH-M50's bass-wise now but much clearer and of course the soundstage is still enourmous, etc.
Perfect headphone for me.