My written impressions are already fairly long and I'm not even halfway done yet, so it's going to be a while longer, especially with my current busy schedule. Will try to get everything done & posted by Friday (including the rest of the pics).
I'll just start with this for today and will post more as more is completed:
- Audeze LCD-XC and LCD-X (amp: ALO Studio Six, source: unknown): As previously said, I was able to get a relatively long amount of time, undisturbed, at the Audeze table on Sunday (about 20-30 minutes), so I pulled out my own LCD-2 r2 for a 3-way comparison.
The LCD-2 r2 was definitely sonically closer to the X, and farther from the XC, though all 3 did share a general similarity (the full mid-range and physically tactile sound). In fact, the LCD-2 was close enough to the X that I knew I didn't have enough time to even start comparing them. All I could tell was that there were a few minor differences, like slightly more treble & bass extension & quantity (at the extremes, not really in general) on the X and more "ease" to the sound. I know it's vague but the X sounded less tense than the 2. Certainly I'm sure that there were more differences between the X and 2, but I just didn't have enough time to explore them, as it would've required extended swapping and music that I was familiar with (there was no familiar music on Audeze's computer).
The XC really sounded like a closed headphone - quite closed-in (small-ish soundstage and more closed-in than the LCD-2), with a lot of bass quantity, enough that it reminded me of the LCD-3's high bass quantity. The bass was deep, thick, and forceful, much more than on the LCD-2, very satisfactory with the unfamiliar electronica on Audeze's computer. Very heavy- and full-sounding as well, and borderline aggressive/upfront, almost Audio-Technica AD2K-ish in its style. It was so upfront it almost didn't sound like an Audeze, it was more like my AD2K in that aspect.
For me the best way to describe the relationship between the 3 headphones: the XC was sort of DJ-ish-sounding with its bass and forwardness (and Alex of Audeze did actually use them later while DJ-ing the Saturday night beer social), the 2 was in-between with its relative neutrality, and the X was like a more refined, wider- & deeper-sounding version of the 2 with more "separation/diffusion" throughout. Informally, I'd say that those who want a clearer, more open-sounding Audeze might want to look into the X. I know that I'm already more interested in the X than the XC and will probably eventually buy one to fully check it out. It was also really classy-looking with the blue-grey aluminum enclosure.
A note on efficiency as well: both the X and XC were noticeably much more efficient than the 2. They were almost twice as efficient, requiring only about half as much turn on the volume knob to reach approximately the same volume level as the 2! I thought this was a welcome change for their amping requirements, as it makes them more easily driven by high-current solid-state low-Z amps like the HeadAmp Gilmore Lite (which I'm currently using, so that'd make me happy if I got an LCD-X).
The LCD-2 sounding like it was between them aside, I didn't think the X and XC were very similar-sounding. It'd be more accurate to say that I thought they were more unlike each other, with the X more neutral (similar voicing to the LCD-2 in that aspect) and the XC more skewed towards the bass and lower mid-range. Neither of them really improved the Audeze comfort level for me either - they were both still relatively heavy and bulky. IMO, anyone who finds the LCD-2/LCD-3 uncomfortable isn't going to get much more comfort from the X or XC.
Lastly, the X and XC weren't all that great to me either, and IMO are just more cases of vastly overpriced headphones and IMO should cost closer to half of what they do - like $1K or thereabouts at most. I oppose this trend of >$1K headphones mostly because I think it's crazy having to pay more than $1K for headphones unless they're discontinued! Neither was especially better-sounding than the LCD-2, and for the price difference I don't think it'd be unreasonable to expect an obvious sonic upgrade, but to me there was none.