What about a Luxman SQ-N100.
Very good combination with HD800.
See also 6moons review.
I only liked the LF w/ the siemens w/ a silver cable, I tried it with stock copper and a silver/gold and I was completely dissapointed as opposed to the EC7. I hear raves with the LG though I don't think that's a slouch.
By the way OP you should take a look into solid state amps as well, GS-X should fare quite well.