Here is the thing on the darkstar.  The current sense resistors are set to limit the maximum current to a little less than 1 ampere.
Which is 1 ampere balanced, or 1 ampere unbalanced. So on low impedance low sensitivity headphones, the current limit kicks
in at less than 10% of the possible voltage swing. Since i have measured current peaks on the he6 at significantly more than
1 amp at low frequencies due to its reactance, this amp turns out to be absolutely no good at low impedances, and due to
distortion, no good at high frequencies either.

If you heavily bias it into class A with a low impedance resistor from output to V- things improve a bunch. But it also
gets way hot, way fast.

If your headphone sounds harsh and bright, then you know it's accurate! Cuz things sound harsh and bright in real life.

So when those harsh and bright things sound doubly harsh and bright on your harsh and bright headphones.... well, you know it's even moar accurate.

Like 400% moar accurate (that's a Joe Grado figure right there!)

"Ultrasones have a unique break-in process; I have not owned the 900s, but I have owned the 750s, 650s, HFI780s, and 700s. They take 180 hours to break in. They will sound pretty good for the first 5 hours and then they will change. At some point the bass goes away and doesn't return until the breakin is complete. Along the way it will be crunchy, flat, awful. Just put them in a sock drawer with the Mexican rap station blaring a little louder than you'd find comfortable for 8 days. I also had the senn 280 - those take 400 hours before they sound good! Most people ditch them long before that, but when you do it right the detail opens up, the range becomes wider, and they become smoother. Go!"

 

...I remembered that horrible looking PRO 2900 graph (even with compensation) I posted on the shoutbox yesterday 
Followed that up by looking at other people's graphs and found out that channel imbalances can reach as much as 7db on the Ultrasone Pro series.

So YEAH it's a burn-in thing, definitely. The drivers need to be burned in so much that they'll start to levitate, and the problems will be solved.

Youve got to be kidding. Ultasones getting better? Really?

Haha, I was being sarcastic, note the levitating drivers inside the cups part.
They're like my guilty pleasure at the moment, since I only use them for listening to EDM sets, movies or gaming. When used with dolby headphone, they project this speaker-ish soundstage presentation that's no match to real speakers but adequate enough. I also absolutely agree that they sound like for music.

i wish he would post his measurements...