I figured I should start a new thread for discussing amp options for the HD-800s, more for everyone else's benefit than mine.
I've had the fortune to be able to try the HD-800s with a few different amps: The Audio-gd Phoenix, which has been my main amp for a while now, the Audiovalve RKV Mark II tube amp, the Luxman P-1 and a couple of others. What most impressed me was how nicely the HD-800s go with the latter amps, being that they are slightly more coloured, the Audiovalve being warm-of-neutral (it did have, in its weird circuit, OPA627s, however, which were probably responsible for that) and the Luxman being a bit closer to neutral, though with a punch bass and overall clarity that makes most headphones sound very good. The cheaper Elekit kit amp was similar in this manner. I had taken a guess from the start that a big tube amp would be the go with the HD-800s and am happy to say I once I got around to owning or testing with tube amps I felt I was right. This is not to say I didn't enjoy them with the Phoenix, as my balanced rig really has a tremendously wide headstage (and soundstage used with speakers, even using the single-ended pre-amp outputs) and is absolutely smooth without having to resort to a rolled-off treble to do it, and for maximum resolution, I haven't bested it, so far, but dead-neutral is probably not to everyone's tastes with them.
There were some very positive impressions from the Canjam 2010 thread about the Apex Peak (and Volcano) and Pinnacle, the former of which would have tempted me had it been balanced and not just single-ended.