well, i really didn't expect this many replies. but since donunus asked, i'll do a quick preliminary comparison between the SR-60s and Denons. For the record i modded my SR-60s slightly, i cut a hole in the pads and reversed them, so they're not entirely stock..
anyway: i think the biggest difference for me in layman's terms is that there's "a lot more going on". whereas with the Grados i heard the vocalist very forward and most other instruments seemed a bit "smudged together" and far back (in general terms), with the Denons although the vocalist is still forward, all the other instruments are rendered quite palpably and sound important as well. so the music seems much broader, realer, engaging, vital, energised (to my ears). i'm not sure if this is soundstage really. and of course, the bass is wonderful and full.
another big difference is slightly less describable, but maybe goes back to what markl was saying about tone i read in the markl mod thread. the denons just seem to add so much more emotion to lyrics and melodies. they sound very real and little fluctuations and intonations in the performer's playing come out much more, which i really like. i don't think i could have listened to the SR-60s without doing something else before i became bored, but with the denons i often seem to drift away from what i am doing..
lastly they share one of the grado's charms in that, although they reveal the very worst recordings and rubbishest mp3s for what they are, anything better is shown to its full potential, or at least it seems like it (although the denons can be a bit more analytical). they also don't seem to shy away from particular genres; hip hop, jazz, rock, electronic, classical, latin.
i guess i should post a disclaimer that you shouldn't read this and run out and buy d5000s! they're perfect for me but i can't vouch that the features i have described are unique to this headphone because it's only one of two i own.
so take it with a pinch of salt.