I have bought my HD 800 just a year ago and I listen to all kind of music (classical, rock, jazz, folk, blues, etc,) except hip hop, heavy metal, electronic music and so on.
I find that my HD 800 is wonderful with jazz and also with classic rock.
My setup is very expensive (as source now I have Naim cdp 555) but when I have bought my HD 800, I had a Marantz universal player as source and a dedicated headphone ampli called "Vincent" that is a hybrid ampli, that is with tubes and transistor. ( believe that it is available also in the USA but I am not sure because I live in Italy!). To me the most important thing to do is to change the custom cable because it is not up in quality with the headphone. For instance Cardas cable make a cable for the HD 800 (unbalanced) that is very good (and not very cheap to tell the truth) and that improves the bass range and give a more natural sound to the high frequencies.