Still typing up my impressions and gathering photos, but as a quick tide me over...

Pono

Boy was this disappointing. Tuned a la Meridian Exploder with dull and congested over warmth. Not quite as bad as that original model but close enough. Also not at all what one would come to expect from the engineers over at Ayre with their clean, transparent resolving and well balanced sound signatures I've heard in the past. Really makes you wonder what the hell speakers and phones Neil Young uses. With all the stiff and capable competition out there in the DAC/Amp/DAP segment these days, one certainly would have hoped for more after everything Neil Young was bitching about. I suppose for people that like that sort of nebulous goo sound, this could be their DAP. However, if one wants a warmer sounding device with better technical proficiencies I would steer them toward the Schiit Fulla (for far less money) as long as it runs in their intended application.

I did try running the Pono via LO into my Leckerton and things do become a bit less congested and a little cleaner from the mids up but still below average in clarity and technical performance while the bass still sound rather soft, indistinct and one-note. As a DAC or All-In-One the Geek Out crushes this thing and already devastated far more competent sounding devices than the Pono (e.g ODAC, JDs Labs, etc).

I also found the UI rather clunky and less than a polished or premium experience. It was very Sansa Clip-esque except with low rez pictures and images. Wasn't the most snappy and responsive, but not what I'd call slow either.

In the end, I'd rather listen to 320kb on my portable rig than FLAC or hirez on the Pono. These things also did quite a disservice to the Audeze EL8's they were paired with. I would also steer people looking to pair hard to drive phones with this device away as well. It is not a weak device but it certainly doesn't have the headroom one would hope for at this size.

Verdict - Decent ears used to decent gear should steer clear of this device unless they need a DAP to serve as a caution marker next to the side of a road.

Well, he had positive impressions about the open EL-8. Just not the closed model.

indeed.
yet if the EL-8 open doesn't have appreciable/better sonic improvements over HE-400i, (ie. soundstage about the same, tonality the same, detail retrieval very similar)
I'm not tossing away +$200 more dollars just for the Audeze name or (heavier) form factor.

Thanks for all the effort wnmnkh and Anax. Much appreciated!

I agree the closed EL-8 was too bright, but I'd also say the open one was bass-light and a tad strident.  They aren't quite finished with the tuning of them yet, so I expect we'll see some changes before release.

Fang's HE-1000 was an astonishingly pleasant surprise. Really clean, wonderfully well balanced, best thing I've heard from him in orthos to date. Really, really nice.

I found the Nighthawk a disappointment. Had a muffled sounding lower mid-range. mid-mids and up were very nice, but I suspect 5db too low relative to the bass to lower-mid range.

Now, did anyone else hear the Enigma Acoustics Darma headphone? No? We'll, holy shit you missed out. A real stunner.  Hybrid dynamic w/estat tweeter.  Crossover at 8kHz. Expected price at $1.5k, I think. This and the HE-1000 were the best things I heard at the show.

Didn't hear it, but Pass labs was showing a new headphone amp. (Not designed by Nelson.) That's one I'm looking forward to hearing.

I agree the closed EL-8 was too bright, but I'd also say the open one was bass-light and a tad strident.  They aren't quite finished with the tuning of them yet, so I expect we'll see some changes before release.

^This! I told Sankar the same thing. I actually liked the EL8 closed more because of that, and I think it's obvious that treble peak is a resonance from the closed enclosure. Some damping should do the trick. Much more musical sounding than the Oppos that have that zombie blur with zero articulation.