I strongly urge you to take the advice above and look at
head-fi.org . They are dedicated headphone geeks and can tell you a lot about virtually any model with an easy search. Like this on the P30:
http://www.head-fi.org/t/559324/review-soundmagic-e10-e30-eh11-and-p30-new-magicYou need to be a little clearer about what you require. They have to be over-the-ear, understood, which rules out the best field-recording solution: IEMs, inner ear monitors, the little earplug phones like the Shure SE series. But you do want some degree of isolation, right? You're not going to get that without a certain size. Phones that sit outside but are smaller than your ears won't give you isolation, and they'll probably leak sound and annoy your neighbors at a quiet folky show.
By the way, you also want to make sure there's no delay between input and output on your R-05 recorder. If there is, trying to record while wearing phones is going to give you a very distressing phased sound.