Here it is, un-editorialized off-my-head thoughts from the private meet today. I'll also quote it in first post because it's probably gonna be helpful info in the long run.
We had both a ss (PWDmk2 -> Burson conductor) and a tube (PWDmk2 -> Eddie Current 2A3mk4) setup going.
The bulk of my comparisons were with HE560 vs HD800; so I’ll briefly go over how the other two (LCD3 and Code-X) felt in comparison first.
LCD3 is extremely detailed and smooth (as much overall detail as HD800 despite a 10 dB difference in upper mids ~ all of treble), but the bass is slow and lacks impact (instead, it is enveloping), the tonal balance also bothers me a bit, the upper end is de-emphasized enough to for everything to feel distant and faded-off.
I felt HE560 was as detailed though a tad more raw in the treble, with a significantly more engaging balance, and IMO superior bass (the impact is substantially more solid, and everything is faster/tighter with the bass, texture/articulation are on par).
There was also a weird soundstage phenomenon with LCD3, where the suction of the earpads create a sort of bubbled-in effect, which is not with HE560 (soundstage is utterly open and projective outward without boundaries).
I didn’t listen to Code-X as much, because I couldn’t get a comfortable fit with the earpads, it still sealed well though so the sonic impressions should be accurate. These stood out to me as having incredibly black background and very fast transients (as fast if not faster than HE560!), and the tonal balance is really neutral, so much so that I couldn’t even detect a describable sound signature.
I found HE560 to be more immediate and engaging to listen to though, some musical cues felt a bit distanced with Code-X (which may or may not be what one prefers, just I value musical engagement a lot). I need more time to listen to Code-X next time as this may only be a case of not becoming accustomed to a foreign sound signature. These Code-X's are by far the most speaker-like sounding thing of the bunch though.
HD800 vs HE560 was a highly interesting comparison, and we had some fun arguments regarding it when we compared the two. Upon critical listening, I found HD800 to still have the greatest amount of treble microdetail extraction (better than anything else), meaning things like the texture of the strings in a violin piece, or rasp of a voice in a vocal piece, but HE560s are surprisingly close in this regard.
Midrange-wise I actually prefer the HE560 to the HD800, as the latter felt comparatively a bit too diffused and lacking in cohesiveness/solidarity, which is again very apparent with good violin/vocal tracks I tested with; both had excellent midrange transparency and were not fuzzy at all.
With regards to the bass, IMO HE560 is better, in two regards: 1) the impact/kick is much more physical and visceral, and 2) for my preferences, the "bass : everything else" balance is better with HE560.
Elaborating on point 1), the test track was ‘Percussion Imaging Test’ from the album Open Your Ears, and while the HD800 rendered the various percussion and drum impacts with authority and plenty of transient detail, with HE560 the impacts felt REAL, like my ears felt the sudden changes in sound pressure with the instruments being played in real life beside me.
On point 2), the test track was ‘Flight’ from the album Man of Steel Soundtrack, and near the final quarter of the track there is a ramp-up in the music from complete quietness leading to a crescendo with tons of drum / brass / other orchestral instruments going off at once, and it was here that I felt HD800’s genre limitations, as I tried to get the volume where the drum impacts were decent, but as a consequence the treble at the peak of the cescendo almost wrecked my ears, meanwhile HE560’s balance handled that bit to perfection, where nothing overshadows anything and everything (from the drums to the brass) was at the boundary of pain threshold at the crescendo, without crossing that boundary. I think that’s a true test of balance and versatility, and HE560 shined in this regard.
Soundstage-wise HD800 is a head and shoulder ahead of all the orthos, not much to say there. In terms of 3D imaging / pinpoint precision, I thought Code-X was on par with HD800, with HE560 following close, then followed by LCD3 and then HE500.
The owner of the HD800 (who hosted the meet) much preferred the HD800 still, I think partly because his genre tastes are more specific and as such the relative strengths of the HD800 outweighed the relative strengths of the HE560 for him. I listen to everything though, and especially for epic soundtrack music as well as synthetic genres with bass, HE560 is a no-brainer.
Misc and loose thoughts
Funnily enough, my uber-modded HE500 was thought as the most emotionally engaging headphone there, despite its relative lack of technical finesse. It synergized fantastically with the 2A3mk4 and presented this beautiful albeit ever-so-slightly-coloured sound signature.
Overall it was a very insightful experience, being able to compare these cans without constraints in time or background noise, on these great setups. I felt that HE560 is powerful enough in technical performance to trade blows with the other flagships, yet the tonal balance is IMO the most versatile, by far. It’s not easy to have both balance versatility and mastery in technicalities, modding HE500 came close, but not quite. Code-X got it down to a tee, with even better technical performance than HE560, though the presentation is different.
Forgot to mention, in terms of comfort? I expected HD800 to be much better than HE560 but no, I actually find the new Hifiman to be more comfortable than HD800 slightly! (HD800’s conventional headband is still less weight-distributing than the HE560 suspension headband, and HD800’s earpads were a bit too thin and I felt a bit of localized pressure along my cheeks, while HE560 earpads just sort of melt around my ears without any localized pressure). Other headphones were so-so in comfort, except LCD3 which was unfortunately very unpleasant to wear, with a massive blistering hotspot on the tip of the headband, and the earpads create this suction effect that is off-putting, to say the least.
How do vocals compare on these phones. I listen a lot to folk and Broadway -- and some opera.