Jan,
By your description, how would the HFI-2000 compare to the HP890? Also, what beyer headphone would you say the HFI-600 is closest in sound to, and how does it compare?
I have casually wondered about these for a while, actually.
edit: The more I think about the HFI-600, the more questions I have. These are closed headphones that give an uncolored sound and have low impedance. Isn't it generally known that best headphone sound comes from designs with high impedance and which are open?
I really wish I could try these. Looking around the ultrasone website, I really like their design philosophies.