Now I'm officially allowed to write about my loaner pair, I'll give some info and quick impressions. First, they are 150 Ohm and seemed to me reasonably easy to drive out of everything from an iPod to my main rig. The loaner pair, which are not final production, are more like what I remember of the HD-800s in overall sound. The frequency response was such that they sound a bit warmer with jazz and classical (there's a drop around 4kHz), but have a treble peak somewhere around the 6-8 kHz mark (as the HD-800s usually do) and, IMO, insufficient bass below 100 Hz to have enough kick for more modern music, which sounds somewhat thin IMO. However, they are very detailed and the imaging with good jazz and classical recordings is absolutely wonderful and the comfort is fantastic. I suspect they are more forward in the mids than the HD-800s were, but I don't have them here to compare. The headphones are so light that I actually complained that the box weighs 4x as much!
I don't reckon the arguments between these and the LCD-2s will be radically different to what the HD-800s vs. them were before. If my feelings about them with the Stacker II are anything to go by, then a good tube amp with them will be the way to go.
Note, however, I have a pre-production pair, so what I say may not apply entirely to the final production version, which I've already been told will have some minor physical changes.
The connector is, as far as I can see, a 2.5mm TS (tip, sleeve) plug. The outer casing of the plugs have a bevel to stop them turning and twisting while plugged in. I reckon the re-cablers are going to have a hellish time with them unless someone gets a custom plug manufactured or gets lucky finding a suitable one.