A) Just don`t. Mixing and mastering on headphones, unless you really understand the response, is utterly pointless.
Mix on good monitors at low volume, and you will get much better results.
No matter what headphones you use, the bass will not be accurate and the mid range will be decievingly up front.
Failing that, in ear monitors are the way forward!!!
I got a set of these recently and they are frighteningly good.
http://www.dolphinmusic.co.uk/page/s...roduct_id/6228