The HD800. Are an extremely detailed , airy , fast , large staging headphone period. Anything different or less is in the chain. And they are fantastic with any genre , it's just people want all the music to sound fantastic on them. Well it will not. The answer lies in many places , Within the chain and sometimes the recording.
I am not saying we all should spend mega bucks on devices to make them shine. A little EQ can make most rigs sound much better. Regarding tube amps , they are the most Versatel and also the most difficult to get correct. As tubes are great I think it is much Easer to just buy a proven amp. And the myth of the tubes warms them up a bit is bull. EQ is a far better way to warm them up on what ever music we are using at that time. The above info is not a rant and just my own personnel view on the HD800.