I like to test out the performance of new headphones (or any other part of an audio system) when I get them. I prefer to do my testing using the best instrumentation for the job that an audiophile has: My ears.
As a result I strongly prefer listening to music with contents that target a something specific rather than a rocking out to a signal generator. I am always interested to hear what other audiophiles and headphone enthusiasts like to throw at their cans and what their reasons are for doing so.
Here's a few of my favorites:
"Bombaclaad Star" by Liquid Stranger - Has a great stretch just after the 4:00 mark where the beat changes to claps and the bass is low. Very low. So low, in fact, that many audio systems can't produce it at an audible level. I use this track to test out bass extension and it's a fun track to listen to while you're at it.
"Rock n Roll Chainsaw" by Maximum the Hormone - The album this song is from is mastered a bit treble heavy so this song makes it easy for me to listen to see if cymbals sound natural (like a cymbal instead of someone saying, "ssss") which is partially how I evaluate my high treble end. It has the added benefit of being one of the funnest tunes I've ever rocked out to.
"Hedwig's Theme" by John Williams - Right out of the gate there's a magical combination of chimes and bells. Again I'm looking for the natural sound of the bells in particular to prove out the high end of my new pride and joy. There's also plenty of opportunity throughout the rest of the track to evaluate instrument separation. Truly a joy to listen to if you're a big enough nerd for it.
"Magnificat 4. Et Misericordia" by Kim Andre Arnesen - I love this whole composition but this movement in particular. I test out female voice production with it since the accompaniment is subdued to the degree that you can easily distinguish between the two.
Please share some of your favorites! Sorry about the compression on the YouTube videos but I'm not sure how else to share tracks here.