Just received these today, here are my first impressions driving them with a desktop amp (Fiio K5 pro).
These are definitely planar transducers and not second grade ones, impossible to mistake them with some cheaper dynamic design. The level of transparency is more resemblant of balanced armatures, but I think it's actually better than the few kilobuck iems I've heard. I don't think I've heard something that transparent in a portable package, except maybe something a bit exotic like the Stax SR-001 or the LCD-i4 which are not closed-back.
For someone used to open planar designs, the sound presentation is quite unusual. The closed design acts like a microscope that highlights every detail and forces you to pay attention to every bit of it. The imaging is excellent, you are completely immerged in the music, no way to escape. If that's your thing it's quite an experience, especially if you're coming from open designs like me. I'll have to see how I get used to them during long listening sessions. The precarious comfort makes it feel like it's going to be some kind of mental test lol.
The tonal balance is quite good overall, I would say it's a bit brighter than an HD600 for instance (but with excellent deep bass), I wouldn't call it a bright headphone but it can get a bit hot sometimes. But it's hard to say if it's due to the frequency response itself or the fact that every detail is literally forced into your ears. It's analytical without really sounding like an analytical headphone. Strange. Let's listen to these more and see how they fare after a few days of use.