The HD800 is not a complete winner, but each excels in different genres.
On a side note, while I had initially preferred the LCD-X to HD800 for being more versatile, I'm coming back to HD800 every now and then because I began to feel that the LCD-X's mids sound somewhat laid-back. I don't know if it's just me, but I find the LCD-X's sound signature somewhat V-shaped, like my previously owned TH900. For me, the midrange is very important, and I prefer it to be forward-sounding than recessed. This is one area where the LCD-3 beats the LCD-X in my opinion... the LCD-X is not necessarily a more neutral sounding headphone than LCD-3 like many people say, but just a tad less warmer sounding one with stronger treble energy. The more neutral sounding HD800 seems to have better mids than LCD-X, too.
This is why I'm eager to try out the upcoming HE-560, and compare its midrange to that of LCD-X. I have an HE-560 pre-ordered.
It's not just you. I'm in full agreement that the LCD-X is a u-shaped headphone, compared to other headphones and even compared to other Audeze headphones. Its upper midrange is more recessed than the LCD-2, LCD-XC, HD650, HD600, HE-560.
Nevertheless I'm getting my particular LCD-X RMA'd to see if the replacement will be better sounding (if they do anything to it in the first place.)
...the discussion about the X's mid-range already started some thousands of posts earlier in this thread...
Some claimed it is V-shaped, some said it is veiled and somhow blur while the majority was always pointing out that the X's mids are amongst the most detailed and balanced they ever heard.
Now, my own story with the X covers all of it:
In the first 2 to 3 weeks it was quite V-shaped. Acually I liked it since it was still on the more balanced side of FRs compared to the HE400 or my Denons.
But then things changed. The mids became more prominent, louder, but at the same time somehow blur.... In other words more quantity and less quality. I wasn't amused. I then started playing round with different amps and did a real hard-core burn-in (white noise 24 hrs a day over several weeks ony interrupted by listening sessions).
Now, to make a long story short, after that burn-in and better matching with amps I do in fact agree with the above mentioned majority... Wonderful mids, all in all a very balanced headphone. Lightyears away from a V-shaped FR.
I got best results with transformer-coupled tube amps and lower output-impendance transistors (resulting in a reasonably high damping factor).
I idedified the critical point for output-impendance being approx at the 4 ohm range. Anything below that is doing very well if the amp can also deliver sufficient voltage... then sound nirvana should be just around the next corner.
Why my X tookT so long to finally "wake up" I have no idea. Maybe there are certain differences between production lots since most others around here obviously didn't need such excessive burn-in to get that result. Anyway, I am glad that my X is now performing to my expectations.