I agree that the Burson is perhaps not the best choice for the HD 800, but I don't think the auditor is a particularly great either... it's pretty pricey for, as far I can tell, it's design and power output.
I realize this comment seems biased (and rightly so as I own the amp, but hear me out), but I would suggest looking at the Concerto as it already has an outstanding reputation with all major headphones, and more importantly it has the specs to back up these claims and impressions. A tube amp is also an idea, however it would work well with the HD 800, but if it is OTL it would not play as nice with a lower impedance headphone such as the LCD-2, or E8, or even your K70X.
For the price, the Concerto is a great performer, and can supply both a lot of current, so it will perform at its best with all headphones. With a discreet and balanced volume control, active ground, and very fast op-amps it is clear there is a lot of technology you get for the price, as well as it being designed by Jan who has a PHD in electrical engineering...
best of luck