Here is an interesting interview with Paul Barton of PSB, where he talks with the owner of Head-fi about getting better measurements on headphones and how that correlates to people's listening preferences, based on the work they've originally done with speakers at the Canadian Research Centre. Think it holds a lot a promise and definitely makes me keen to try out the NAD Viso HP50.
http://www.head-fi.org/t/754530/an-interview-with-paul-barton-of-psb-and-nad-head-fi-tv#post_11308414
http://www.head-fi.org/t/754530/an-interview-with-paul-barton-of-psb-and-nad-head-fi-tv#post_11308414