Oldschool Accept (either "Restless and Wild" or "Balls to the Wall") are my heavy metal reference test albums. Love the way those two albums are recorded. Not my favorite metal band by a longshot, but definitely my favorite metal recordings, although Reign in Blood is right on their ass.
On the opposite end, I was listening to the classic "Rising" by Rainbow and it really feels like they rolled off everything after 8khz or so. There just...isn't anything there. I thought it might be a clogged channel or something, but everything else sounded fine. Would explain why that album always sounded somewhat dry...
I love using the HD800 to listen to crappily recorded music.