Guess I'll crap on the HD800 considering this is the proper place.
To me, they're lifeless no matter what I've heard them on. That is, they're just not for me. I disagree that the HD800 is just so different from the 009.
They really do share the same approach, it's just the 009 does everything right, for me. The 007 is warmer and veiled compared to the 009, but it's still
more resolving than the HD800. The HD800 gets soundstage and imaging right, those are tops, but it's still a headphone that has never moved me.
It's still technically one of the best headphone around, but that doesn't equate to enjoyment, same can be said for the 009 - too resolving, not dark enough ,etc.
I'd love to hear the HD800 out of something that is considered beastly i.e. Leviathan, I've heard 'em out of LG, LAu, EC onslaught and they were never transformed.
I don't believe any amp will morph any driver into something it's not, but I hope to achieve the absolute best for my 009 with a DIY T2.
I will say however, a good $2.5/3k can land you a KGSSHV which is an absolute wonder with the 009. That could totally be endgame, if you wanted to stop chasing the dragon.