VRacer-111
1000+ Head-Fier
EDIT: Holy ****, I definitely get the semi-open comments now! They don't isolate well at all and I can hear everything around me (and I was going to use this in my office... might have to rethink that).
EDIT: Comfort after half a day of use... not good. Really bad in fact. Hurts on the top of my head. Quite poor headband compared to the Ultrasone Pro 900 I've been wearing daily for two years now without any issue.
While they are semi open and you can hear outside noises, they don't leak sound like you think. More than well enough to use in an office with no issue. Play music at your listening level and put the earpads together...you will hardly hear ANY sound at all from them, unless you listen at rediculously loud hearing damaging levels...
Comfort is not the best with the headband, but it's not too bad to me no issues wearing for hours and hours on end. If you want a horrible headband for comfort try out the Philips A5-PROs...However, the stock earpads on the TH-X00 absolutely suck for comfort.