I don't know if anyone has mentioned this before, I can't imagine no one has, but the DK2 has a very unpleasant smell about it once it warms up. The unit isn't hot, as far as I can tell, so it's not a burning smell. The smell reminds me of the first run of Line Dice, a game I created and had manufactured through a chinese company. Something used in the manufacture of the dice left behind this terrible smelling residue that gave me a headache if I smelled it too long. And since I was bagging and packaged all of the dice by hand, I got to smell it ALOT.
The interesting part is that when I got the second run of the dice made, they talked me into paying for whole new molds and the second run of the dice had no residue nor smell. It was like they were using an entirely different kind of plastic, or maybe a different industrial lubricant to remove them from the mold. The smell was gone and the dice are clean enough to eat off of.
I'm thinking one, or maybe more, of the components inside the DK2 has that residue on them that is making that terrible smell. Without disassembling and cleaning every part by hand, I think it always will have it. I know, after a year of storing my dice, the smell did not go away on it's own. It's like an oil, and it doesn't evaporate. You guys at Oculus should be very careful with your consumer release as to not use parts with this substance on them. The Rift can be hard on the eyes and brain by itself. The last thing you want is some minor manufacturing chemical on the units to add to people's potential headaches.