I got a pair (the "Truth" edition - cute names) last week from Danny in Singapore and have put in about 50 hours of listening.
-My reference point is a pair of Klipsch X10s while on-the-go and a vintage pair of STAX Lambda Pros paired with the SRM-1MK2.
-Two caveats: I've never owned a DAC/amp better than a NuForce UDAC2, so you can take my opinions with that grain of salt; also, I'm now invested in these IEMs and want to love them.
-Listening-wise, I prefer a rich, clear/natural and mostly neutral sound but fast and with a wide sound-stage with good separation/imaging. Basically, I love the STAX sound but could do with a slightly fuller bass compared to what the old Lambda Pros offer.
-For listening, I've been using a Google Nexus 5 with Google All Access music downloaded in high-quality - I believe 320kbps MP3
But on to first impressions. These are, in a word, amazing. I tried these first right after listening to a STAX 4170 and found myself really impressed with what they can do across genres. Listening to jazz, all the instruments sounded real, from the warmth of a sax to the pluck of the bass and the timbre of the piano. With classical, the warmth of woodwinds and whine of the strings was perfect to my ears, just like being at a concert. Electronic and even dubsteb (had to give that a shot!) had all the speed and dynamics necessary to sound exciting, with plenty of punch to the bass without being over-the-top and maintaining the clarity to separate vocals and synths. Pop has nice depth and clarity, and the detail there is really incredible. A surprising find was that rap/hip-hop is fantastic; these really remind me of STAX when it comes to speed and the clear reproduction of vocals; they have all the presentation of a person actually speaking in your head.
While I didn't get the STAX experience of being at a jazz club when I close my eyes (I think largely because of the isolation vs. open back design), the sound-stage is still very wide with the same detail if not more -- I actually found myself hearing a few things that I didn't remember before from my Lambd Pros. There's a richness to these that's very pleasant, with no area of the spectrum overly accentuated or muddy. Plus they seem to be accommodating of a relatively low-end source -- my Google Nexus 5, unamped -- so that's great for the lazy. I'm still trying to figure out if I notice weaknesses -- perhaps the mids are a bit recessed, so just a tad v-shaped? And while the bass is full and tight, it's not boomy at all, which I find a relief. The sound wasn't fatiguing, although in terms of listening, I did find these to get uncomfortable after about 5 hours of use. On the plus side, they blocked the noise out of a 24 hour flight from Singapore to NYC enough that I could still appreciate the detail on my tracks, so no complaints there. And they felt good enough that I was still wearing them when I deplaned at JFK.
Construction is great, as they feel rock-solid and durable. They're comfortable with a quite customizable fit. I'm hoping that with more use my ears get acclimated to them so there's no soreness after full-day listening sessions. Also, it's a nice bunch of accessories, though with the thick and stiff "Truth" cable I do find it a bit hard to fit these in their case. The leather case in particular seems too small for the big cable, and given the attention to detail on little things (e.g. the window for the silver cable, the raised dot on the left-side IEM to recognize it in the dark), it would've been great if there was some sort of clever cable auto-winding system built into the case.
Quibbles aside, I'm extremely pleased with these - they've taken the clarity of the Klipsch X10s and boosted it across the full sound spectrum with much improved clarity, richness and isolation. To me, these are in-ear STAX, and I'd love to try them with a really high-quality DAC/amp just to know how much more I can get out of them.