Ok it's modding time now. Been experimenting with my one for a bit just now. I'm currently not using any of my wooden cups but I removed the stock outer housing cup, gave it a listen with it being open, the sound was a bit shrilled (bit of sibilance) and with some electronic music the bass is quite funny sounding sort with a fake timbre and all. So decided to pull a few tricks of my past HD580/600/650 mods as the driver capsule is designed very similarly.
There is a piece of round slightly dense foam wedged into the top of the drivers housing on the 003 which beneath is a white felt glued on, the felt actually controls how much air is pushed through into the driver cone itself, use a pair of tweezers, remove the foam and run the headphones open without any cups. I'm listening to some 24bit La Mer Seascapes Allegro from my desktop > 3.5mm out to my custom 18v Banzai Cmoy using dual mono AD8597 (a single 8599 IC) and the sound is a lot more neutral with the classical stuff, soundstage is a bit more 3-dimensional maybe a bit more further out on the 4th or 5th row but really surround sounding (prior to the mod it sounded really closed in and laid back or shelved), the sound is also maybe a tad bit brighter, bit of warmth has been removed sounds bit more neutral now. I'm suspecting detail retrieval is a bit revealing but not incremented due to being fully open and bit brighter sounding.
Will be playing around with the dampening baffle and turning the stock outer housing cups to a open form factor with grills (resembling my HD600's a bit).
The sound is actually a bit more like a pair of bright headphones slapped together with the dark/laid back signature of a HD600/650. So far it has less bass than my HD600's bit more neutral sounding to my ears with classical. Soundstage is a bit wider in terms of 3-dimensionality, detail retrieval seems a bit more than the HD600's possibly due to the sound sig being more brighter, the HD600's have better bass but no where near basshead level (both of these can's are not basshead can's) and the soundstage / sound is a bit more intimate sounding on the HD600's.
Will be reporting more results back.
EDIT: Gave my LCD2's a listen and did a comparison, really impressed with the subtle differences between the two for classical music, the sound on the 003 is more fun and serious at the same time.