I took delivery of the LCD-XC today and spent a couple hours obsessing and running through the acid-test tracks. I have LCD-2 rev. 2 and LCD-3 (new build) on hand to compare. After listening, I also received the email with the response graph from Audeze for my pair of LCD-XC and compared it to the LCD-3 graph. The response graph confirmed what I hear, which is that the LCD-XC has a boost in upper female vocals, trumpets, violins, snares, presence, etc. relative to the LCD-3 as well as a warmer but firmer lower end. I cannot discern any downsides of the closed-back as I can with my Fostex TH-900 and TH-600, which have in-cup resonances (but which I like very much sometimes; they're exciting and tremendously dynamic). Also, unlike the new AKG K812 that I got this week, the presence-area boost is clean, not ringy and ragged, and the bass is heavenly clean and rich. The XC does not have the super-beguiling velvety quality that I like so much in the LCD-3 that makes them my go-to cans for almost all pop/rock/jazz, but it does a great job giving life to choral works and older analog classical recordings. Nevertheless, I still prefer my trusty T1 (new build) for wide-ranging listening sessions across genres. I know that puts me in a minority -- why do people rag on those so much? I've always been totally captivated by them.
The LCD-XC is quite heavy, and I would not use it except in a stationary position on a couch, comfy chair, or in bed. That said, those are about the only places I listen to cans anyway! I have a doctor buddy quizzing me about them for use at his office desk chair, and I can't recommend such a big, heavy can for that -- it's T1 all the way, baby (he has Fostex TH-900 and is thinking of a change since the TH-900, though closed, leak quite a bit and are sort of loosey-goosey on the head).
Let me disclose that I have deeply rolled-off hearing above 12khz and a pretty significant dip in the presence region in my right ear that skews my balance to the left, so obviously my preferences have to reflect my own deficiencies. I'm 48 and have been deeply into audio since I was 13, so I've got some experience behind me.