I'll paste an Amazon review that I wrote containing everything I currently know about these:
I got a chance to hear these as a local Guitar center and they sound awesome! I WAS headed in to buy the Sennheiser HD 280's (Pro) until I heard these. The 380's completely blow the 280's away. There is JUST no comparison.
The Bass response is amazing for closed ear headphones. This is quite rare from what I understand.
You can hear all the detail in the highs and mid-ranges and everything sounds crystal clear. Close your eyes and you might think you're sitting in a concert hall.
Since Sennheiser still does not have anything about these headphones on their web page I e-mailed them for info and got the following:
Product Features
Collapsible high-end headphone for professional monitoring use
Highly advanced features for superior sound-monitoring- Extended frequency
response for accurate, reliable sound reproduction- Increased sound
pressure level (110dB) to handle demanding use
Closed circumaural design for excellent passive attenuation of ambient
noise (up to 32dB)
Exceptional comfort for extended listening
Carrying case included for engineers on the go
Replaceable single-sided, coiled cable with 3.5mm jack connector and screw
type adapter to ¼"
Easily replaceable parts for long service life
Headphone with detachable coiled cable, Carrying case, ¼" jack adapter
Technical Data
Connector 3.5 mm plug, straight (separate ¼" jack adapter included)
Cable length 1m coiled, extendable up to 3m
Frequency response 8 - 27,000 Hz
Weight 220 g (excluding cable)
THD < 0.1 % (1kHz, 100dB SPL)
Impedance 54 Ohm
Transducer principle Dynamic
Sound pressure level 110 dB (1kHz, 1Vrms)
I can only find 2 places that sell these headphones right now. Musicians Friend (and thus, Amazon) and Guitar center.
Oh and another thing, the sound isolation these things provide is SECOND To NONE (Except maybe the 280's)! Even with the volume extremely low I could not hear people talking who were standing 3 feet away from me! I was listening to Guns N Roses when one of the sales guys fired up a Bose system in the same room... it was so loud that (without the 380's on my head) I couldn't hear people talking but with the 380's on I barely heard the music coming from the Bose system.
These are totally worth $200!!!! And I'm not even a hardcore audio guy. If you don't believe me just demo these things are your nearest Guitar Center! Take your current headphones with you so you can compare them.