It does seem like the LCD-X would be one of the most appropriate comparisons with the Abyss, judging by all the impressions I've been reading from people.

Also interested to see how the even lighter diaphragm plays in resolving power as well. 

Things look a little smoother from 2k to 10k in leakage mode as well... methinks...

Not quite related, but this brings up to mind a criticism (from Tari I think?) that he felt the Abyss was lacking warmth or body. I actually don't disagree with this assessment, especially when the Abyss is run fully sealed. The "leakage" mode brings about extra bass, giving the Abyss a slight fun U curve (so one simply enjoys and forgets these kinds of nitpicky things.)

I too recall one setup at THE SHOW where the Abyss was on the cooler sounding side. Akin my to subjective impressions of the cooler tonality of the SRH840 or K701; or even the TH900 (with its depression the "fundamentals" region.)

I surmise that this aspect of the Abyss may be caused by several factors:

• The moderately wide bump at 1kHz - relative to the warmth / body / fundamental area from 150-600Hz (see graph below)
• Low D2 distortion in the mid-bass
• A good treble presence from 7-10kHz
• The DAC

HE-400 has that same type of peak at 1khz, but it's a very warm sounding headphone.  Its broad upper-mid recession probably helps a whole lot with that though.

Most planars have some tension to the diaphragm. In the case of orthos (SE or not), there's something on the CSDs which show how tightly tensions the diaphragms are. If you guys remember, I did an analysis of the LCD3 a while back, comparing "veiled" LCD3s to "good" LCD3s. I've also added an HE-400 CSD measurement for better comparison. Gurubai (the resident ortho expert) among others surmised that the "Ortho Wall" ringing was probably indicate of the diaphragm. Whatever it is, I think it's safe to say that this "wall" can be seen on ortho CSD measurements.

The most crucial point I will make is that I don't hear any of of this "ortho wall ringing" with any of the headphones below. I mean I would hope that none of us here look at the LCD3 CSDs and go "Wowza! POS! OMG! WTF for $2000?" As John Atkinson pointed out in his PPT slide at THE SHOW 2012: "Measurements Lie"

The results (and subjective impressions) would certainly jive with Joe's explanation to me:

With CSD's, we've found the decay around 8-9 kHz to not be the driver, but acoustics. I chased this down for quite some time when going through various gasket materials and cut dimensions just to find I was chasing a ghost; taught me all about the wonderful world of CSD's-:)

Or this one (from a post deleted from HF):

In fact, I chased the CSD's for a good week or so prior to release only to come full circle to determine that this measurement, at least as it pertains to this design, was of no use in improving upon the final sonic character...