foxyproxy
If I could pick only 1 track to test headphones with, it would be this one. Its got the works. It goes through pretty much the entire frequency range. Can test the action, the bass response, the sibilant areas of the treble and it also has spacial sounds in it to test the soundstage with. To top it all of it has these little quirky noises that are somewhat hard to pick up on some headphones. Just amazing.