Hi Pedro,
Well the uplifting trance stuff I'm familiar with. I have Kalopsia, and it sounds much more defined in proper bitrate (mp3/lossless/wav) than on YouTube. The D600 is perfect for this music. In Kalopsia the vocal sits well within the mix, and the bassline is well represented. Combined with a spacious sound.
For London Grammar, the YouTube codec again is holding this back a bit. There should be more definition on the top end. So I recommend using high bit rate mp3, lossless or cd quality. I know these links are just representative.
The d600 do an excellent job of space here. Vocal clarity is excellent. The only caveat, as I've mentioned before, is if you tuned down the bass a couple db it would be better for this track. Not. A huge deal, as the d600 has such a nice low end, but it can be a bit too present on some tracks, and compete with some of the lower mid range IMO. A the vocal is still clear, however. Again, I think this is the compromise, that this dynamic driver headphone can produce great bass but should be tamed for more reference listening. Not a problem, it's just the nature of the headphone. Perhaps planar magnetic are different in this respect. Will have to hear some soon.
Importantly, listening to James Blake Overgrown, the bass is great for this musical style, and the bass doesn't compete with the vocal. Everything else sounds lush, transparent and clear. You wouldn't enjoy this track the same way with HD25, you'd lose the rich, clear, and wide presentation.
On Biffy Clyro, no adjustment is needed. For this type of engineering and pop style production, the d600 is fine. Again vocals are well represented and not recessed. i'm beginning to rethink the d600 mid range. It's quite good. Certainly the clarity is there.
What you'll find with all of the above is that you can listen for hours, at comfortable volumes, hear everything, and feel all the impact. One of the reasons I like the d600 so much.
Quite familiar with Limit to your Love, and this is one of the first tracks you should listen to after your D600s have burned in (not sure if this is legitimate, however, I do feel my d600s or perception of them change greatly after a day or so of owning them). This is one of those tracks that people only hear the vocals and percussion, but not the sub bass if they have regular headphones or no subs.
In comparison with the HD25 with this track. On the Hd25, pianos are notoriously flat and compressed sounding (not just for this track, but most other piano recordings, the Amperior fairs better here). But where the hd25 and the majority of headphone will fail begins right at 0:51. What might just sound like wind rushing, the d600 is already producing the sub bass. When the wobble finally hits, you can hear it on the hd25. On the d600 you can feel it. The d600 produces a low end that the hd25 just doesn't represent. As a result, the performance on this song and many other is vastly superior on the d600.
So you are getting superior instrument separation, staging, clarity, soundstage, high end, and sub bass with the d600 over the Hd25.
But i am more the type og guy that would buy the d600's and a amperior first and still save 100 euros.... 