I'm not going to tell you which headphones to buy. (For the record, I use Bose Quietcomfort 2 noise-reducing headphones, which kick ass.) Put together this mix, and don't sink any cash into your headphones until you're sure they can handle these songs in style.
The Mono: "River Deep, Mountain High," Ike and Tina Turner
Headphones bring out the stereo effect in songs more than any other listening system, but they should still be able to handle a serious mono song. This track features perhaps Tina's best vocals ever, standing on top of a wall of sound that's as strong as any that Phil Spector ever built. What to listen for: In the final crescendo, how many different instruments can you pick out?
The Bass: "Love's Gonna Get 'Cha," Boogie Down Productions
Bass is where headphones will most often let you down. This classic BDP track is made up of almost nothing but boom, boom-boom under a drug-dealing morality play from KRS-1, so it's easy to focus on the low end. What to listen for: You want to feel it in your teeth.
The Subtlety: "Song to the Siren," This Mortal Coil
This spare, mournful track (a Tim Buckley cover) focuses on a few strings and the gorgeous voice of Cocteau Twins singer Elizabeth Fraser. Use it to check how well the phones pick up small details. What to listen for: With good 'phones, you'll hear a slight increase in the background buzz just before Gerrard starts her vocals. Also, try to pick out the whispery overdubs.
The Stereo, Part One: "Are You That Somebody?" Aaliyah
An early display of Timbaland's brilliance, this rattling, cooing track is a feast in stereo. What to listen for: Check how Timbaland alternates between center-set vocals and vocals with a slight delay on one side. The former sound like they're coming from the middle of your head; the latter seem to surround it.
The Stereo, Part Two: "Telephasic Workshop," Boards of Canada
This track rests somewhere between neo-psychedelica and sheer madness. It attacks from both sides. What to listen for: As the song builds to its peak (a little more than three minutes in), snippets of human speech stutter in both ears. Listen first through one ear, then the other, then put on both headphones to hear it together.
The Total Package: "The Gash," The Flaming Lips
This climactic track from The Soft Bulletin will put any speakers through a full workout, with a multitracked chorus, booming drums and swirling stereo sounds. What to listen for: We're going for goose bumps here.