If going cheaper I'd go Matrix M-Stage HPA-2 w/USB DAC. $320 for the best amp/DAC combo under $1k with the HD800, IMO.
Over that mark you start getting more options, Bryston BHA-1 (solid state, $1400), Eddie Current S7 (valve, $1800), Eddie Current Zana Duex (valve, $2200), DNA Stratus 2A3 (valve, $2700), Headamp GS-X mk2 (solid state, $2800) and on and on.
Senn's amp is not very good, the Little Dot is OTL, but I doubt it's ability to drive HD800s well. I've read that the Phonitor and HD800 are not a good match due to the Phonitor being too warm and masking detail. I've never heard any Creek product, or heard of Shange/Raccoon.
Schiit Audio will have it's top of the line Ragnarok solid state amp out very soon and we're all hoping it works well with HD800s. It will run $1500 and also be able to power efficient speakers.