Wow, great impressions already, so will just add a little.
First off, the biggest surprise for me has been the hf-2's and the Audeze planar (I will attempt to get pictures today). The hf-2 is remarkably good, as long as you like the Grado sound. Sounds to me most like a mini PS-1, with reduced bass. That is a plus in my book as the PS-1 has always been too bass heavy for my tastes. The real shocker has been the Audeze planars. These are very fast, clear phones with a great frequency balance. They may lack a little low-end weight but that is definitely IMO. A big chunk of that comparison was using them on a Gilmore lite fed from the Spectral 2000 DAC and a PCDP transport. I compared them to an O2/BHSE using the same source, so not a liteweight comparison. The Audeze kept up in clarity and speed, but not in midrange smoothness or bass extension (WooHoo big surprise with the price differential). At $350 - $400 dollars, this phone is a steal. I will try to get a listen to it on the GS-X/Neko Audio D100 rig today.
Which brings me to the Neko Audio D100. This is the real deal. Listened out of the GS-x on my K340's with a Macbook feeding it via optical output. Very smooth and clear with a variety of genres (rock, classical, jazz). Definitely to my tastes as it, like the GS-x simply gets out of the way so you can hear the recording in all its glory or with all of its faults, but the it does not accentuate the faults in the recordings. It lets you hear them but doesn't throw them in your face. I want to go back and listen to the Audeze planars on this rig.
The HD-800's were awesome on both Al's Luxman and the Headroom BUDA. Others have given good impressions. IMO the impressions vary because this phone lets you hear the upstream components in all their glory (or not). Very electrostatic like speed but you have the advantage of dynamics of dynamics. Can't really say much more without more listening time to see how the electronics are influencing any other specifics. It looks like I will own this but I'm definitely going to let the dust settle first.
OK I need to go eat something and drink at least a gallon of coffee ... I guess I need to look for Billy.