And if you're ready to buy a almost 2000 USD headphone, you should consider the fact that there may be better amps out there than O2.
HD800 is a tricky beast to drive correctly. Driving it with a O2 will add you to the "No bass, harsh treble"-subcategory of ex-HD800-owners. Sure LCD-3 ain't that easy either, but LCD-3 will sound more like it should out of a O2.
Great! So please, could you elaborate a bit more on how do you like both headphones with this amp? Also, could you answer my questions from the first post about 3D rendering differences between both headphones, imaging, overall balance etc. I would appreciate it very much!