I write this as I'm letting my HE-1000 V2 go; this is more a short comparison of how I experienced my HE-1000 V2 versus my HE-6se V2 while owning them both and not necessarily a thorough breakdown of their abilities.

When you have a new HE6 and it's not fully burned in, but it's extremely close and just needs to be driven hard a few times, those first few times giving it the current it needs, it develops a very holographic and immersive stage that's very forward and aggressive, yet wonderfully liquid, warm, and detailed. It delivers a wide stage that's not quite like being in the room with the recording, but elements can be so very close and forward that it's staging is much more like being immersed in the recording. When it burns in fully, the driver becomes more efficient and takes on a slightly different voice, warmer and smoother; the holographic quality reserved to when fed high current becomes its normal state.

This final HE6, of very warm leaning and slightly less aggressive tonality, is very different from the HEkV2, however, at high current (and the HEkV2 doesn't need anywhere near as much) the HEkV2 displays a very similar sonic character to the almost burned in HE6. It's staging is also like being immersed in the recording, however, the stage is further away; its delivery more like watching a stage from a few seats back, near enough to be close, but not forward, nor distant. There's also a gigantic verticality to the stage, not displayed by the HE6, which is much more horizontally lateral in delivery. The HEkV2 has a very full sound that leans bright and airy, but can be warm or rich, and has an excellent tonality. The dynamics of HEkV2 are totl for a planar, but doesn't compare to some electrodynamics from Focal, nor estats, and its sense of separation is totl period, better than most things I've come across. The most unique thing about the HEkV2 would probably be that, compared to the much more aggressive sounding HE6, it's a gently voiced headphone that kind of doesn't care what's thrown at it. It always sounds like itself, soft, yet incredibly detailed, it's consistent and spacious.

Lastly, the HEkV2 uses its verticality and its speed to image. It has a very fast attack that's quick like an estat, but unlike estats (namely lambda), which deliver sound in very fast 2-D layers creating excellent depth, creates images by quickly attacking from various points along its tall, vertical driver to create depth. It's a quality I've never seen mentioned in any review I've ever come across for it, however, when I first placed it on my head, it was extremely noticeable, and to me, felt unnatural (probably because of my familiarity with lambda). One other thing I'd note about it would be that with its unique treble tonality, female voices are sometimes off, excellent in tonality, but not true.

Plainly, I could say that the HEkV2 is a vastly superior headphone, and in writing this, I feel like a lunatic for letting this go, but interestingly, I'm letting this go because I actually really like my HE6 a lot more. Both are excellent, they share certain qualities and are distinct enough to both be kept, but I definitely prefer the HE6 over the HEkV2, possibly because I listen to a lot of female vocalists. Female voices are something that the HE6 handles much better than the HEkV2, whereas, the HEkV2 probably defeats it in every other category.