I am not an expert but from my experience, LCD 2 and 3 are quite different, they share similar Audeze house sound (very engaging, lush and emotional) but LCD2 has more kicks, more dramatic and LCD 3 has more tamed and refined sound(bigger soundstage, depth..). HD800, of course, has very different sound signature from LCDs(wider sound stages, fast, energetic but thin, less engaging compare to LCDs) . I would put LCD3 in between LCD2 and HD800 but more on LCD2 side.
my best way to describe the differences between Audeze sound compare to HD800 would be having a very good tube amp(Audeze) vs Having a very good SS(HD800) amp.
Soloist wouldn't be the best amp for all of these headphones. I had W4S2-Soloist-LCD3(loaner LCD2,HD800 at this time) and I liked LCD2 and HD800 better than LCD3. Also I like LCD2 and HD800 with Woo Audio WA6-SE when I had it.
IMO It is very hard to find very good matching amp for LCD3 and HD800 unless you want to spend $2K+, but I have a very limited experiences in amps, for example I haven't heard Schiit Mojos or BHA-1 which seems to suite both LCD3 and HD800 pretty well.
Like most of them said, I highly recommend you to hear them yourself. If you have any audio shop who carries them or even head-fier's close to you might happy to give you an audition.
Edited by senson - 7/4/13 at 6:55am