I've had "expensive" headphones for 5 or 6 years now and I've always purchased low impedance headphones so things like laptops can drive them. I currently own the D2000s, which has a really low impedance of 25 ohms.
What advantage do high impedance headphones have? Are they really that much better sounding? Am I missing something by only owning low impedance headphones? I'm getting that 2-year itch to buy a new pair of headphones and I'm not sure if buying higher impedance cans will really make a difference.