Just about any song on the Causeway album by Ryan Teague. Reaaally nice from the HD-600.
Valerie June - "Pushin' Against A Stone" - red wine or Tasmanian whiskey - stunning even sober
Lisa Hannigan - "Sea Sew" - red wine
Sierra Noble - "Possibilities" - very good beer or red wine
Nikolai Demidenko - "Scarlatti Sonatas" - sobriety & dark room - "maybe" red wine
Regina Spektor - "Far" - red wine or whiskey
Joe Creighton - "Holywell" - red wine
Missy Higgins - "The Sound Of White" - red wine
the list above covers a lot of musical spectrum
Mary Coughlan - "Sentimental Killers" - red wine or Tasmanian whiskey
Pavlo's Dog - "Pampered Menial" - very good beer, red wine or good Tennessee whiskey
The Fabulous Thunderbirds - "Girls Go Wild" very good beer
the Crash Test Dummies (debut) - "The Ghosts That Haunt Me" - very good beer, red wine or whiskey
Most MUSE can be pretty amazing on the right setup.
Namely, all three parts of the Exogenesis Symphony--this can either be tear-inducing or headache-causing--such a complex and wildly varying piece of music. I think it will tell you a lot about your system.
Madness is a song that sounds very cool through any decent set of cans.
Some other favorites through the headphones (in no particular order):
Holocene - Bon Iver - just plain sublime...
Yoshimi Battles the Pink Robots PT. 2 - Flaming Lips - may induce joyful vomiting...
Most Radiohead - too much will leave you in a depressed state...but it may be worth it
Most Air - warning: too much and you might find yourself enjoying Muzak--and we don't want that to happen...
Most Massive Attack - Atlas Air would be among the top along with Rush Minute
Daft Punk - Get Lucky (kind of annoying song but it sounds sweet through a quality setup) also End of Line (from Tron) - this sounds SO cool through a high quality system
Dire Straits - Money For Nothing and Sultans of Swing - Mark Knopfler's guitar work pretty much always sounds amazing through good headphones--kind of like David Gilmour
Loreena McKennitt - Snow - Gorgeous piece of music
Any Norah Jones from her first couple albums - voice that makes you melt...