Listened to the Audeze LCD2, the Sennheisser HD800 and the AKG 812 at a dealer today with my own music. Transport was an AK120 and a Bayerdynamic A1 amp. First off all the headphones had parts where they were the best. Anyways, here is my completely personal and biased impressions.
Design, fit and quality: (Not so relevant for the sound I know, however...)
-The LCD2 is build like a tank, but is heavy and pushed annoyingly on my ears making is super uncomfortable for me.
-The AKG feels very well build and looks stunning to my mechanical-ingineers eyes. The surface treatments everywhere are just very well made. Much better fit than the LCD2, especially the earcups are very nice and comfy. Although the cable is thin, this one-sided type more comfortable to use than the dual one on the HD800 that makes me feel like I'm wearing a bib (Ok, not quite that bad..).
-The HD800 looks like it came from a 80s sc-fi movie and the earcups are visually super large compared with the rest. I don't like the design too much as you can probably hear. Seems well build though, but confusing to my eyes and there are these weird soft feeling silver sides that my finges tough when taking them on an off... Makes me go "Hmmmm".... They are just as comfy as the K812 on my head but when moving my head the headband had a tendency to glide back and forth giving an insecure feeeling. Feels just as light on the head as the K812 and I would be happy wearing it for hours.
-> overall winner to me was the K812. The HD800 just a bit behind.
Sound (the tough one)
-LCD2: Amazing deep bass. Never heard anything like this. Very hard to say anything bad about that bass -wow!. However... In my head the sound was significantly softer and less controlled in the mids and especially in the high-end than the other two. I can understand that some might find this HP amazing, but to me it was an absolute no-go. It confirmed to me the importance of hearing for yourself rather than reading reviews
To me it was a 550HP Ford Mustang in headphones..
-K812: Very exciting sound that got my feet rocking in 2seconds. Good deep bass. Even better mids and well extended hights. Somehow artificially sounding to me, albeit it's hard to explain, but going back and forth between the three somthing was amiss in my book and I was thinking about the headphone rather than the music. Still... The above is somewhat exaggerated to make it clear, in reality it was quite close sounding to the HD800, much much more so that the LCD2.
-HD800: Wow! This is music to me, I have the feeling that this is how the music sounds and I forget the gear. The bass was in my ears a little bit less extended than the K812. I think this HP would take some getting used to though since I almost get "overload" of information to my brain - in a good way
Something bad beyond a bass that does not reach LCD2 levels? Maybe a bit analytical, but just a bit; but I kind of like it that way.
-> overall winner to me was HD800, with the K812 strong in pursuit. Before going into the shop I had read a lot online and was almost sure that I would prefer the K812 and have the LCD2 and HD800 following a little bit behind. After the review my personal (!) ranking was different...
Value (Swiss prices, 1CHF ~1.12US$ ~0.82€)
-LCD 2: CHF1400
-K812: CHF1950
-HD800: CHF 1300
-> overall value winner to me was the HD800. With a different price on the K812 (such as the same or lower as for the HD800) I would be somewhat tempted, especially since I have read that they can play well on portable gear, even an iPhone, which would be really nice once in a while. But in my country it is very hard to see the reason for another CHF650/US$730 for the K812.
Well... today I learned the hard way that it pays of to have a good local shop with knowledgeable people and time to listen to different gear-combinations.... Hope that I can now find a place to listen to some stax gear and a HD800 before I finally decide...