Hi! I'm looking for good headphones which will be mainly used with my PC. My problem is, that I live in a rather noisy environment so I want closed headphones with good noise cancellation. I have narrowed it down to three: 1. Sennheiser HD-280 pro: I know some people recommended those on this board already but then again I read they don't perform quite as well as the Sonys. 2. Sony 7506/ V6: Are the 7506 and V6 the same? How is the noise cancellation? 3. Beyerdynamic dt990/ 770: Anyone have any experience with Beyerdynamic? Thanks a lot!