Well, I've gotta say... I bought a set of these for "portable" listening with my Zen Vision, and they've ended up ousting my HD555s in a total of... 27 hours. Absolutely amazing definition, and even though they're horribly overpriced in Canada ($105 CAD retail), I can't honestly say anything bad about them, except that the senns are much more comfortable for home listening. Thanks for everyone's reviews and recommendations!