Following up on this thread - I hope we see more offerings in this category in the future. In the future I plan to get a headphone setup which will be equalized according to David Griesinger's method, which seems to me to be the best method available (you actually get an eq which suits your individual ear):
The RME ADI-2 is excellent, of course, but it only has five eq bands. I'm not sure if that's enough. The minidsp ha-DSP seems very functional, but is it powerful enough? I like to have some extra power available. I'll probably be using the Sennheiser 800S if I come across a second-hand offering.
Given that
@amirm has began to popularize the idea of headphone equalization (hats off!), it might be that it will become more common with standalone products who do this.