For breaking in, I usually use white/pink noise. But frankly, there is no right answer to it. Hell, we don't even have scientific proof that break ins work.
For testing, I use music I'm familiar with. Good masters are a plus, but poor recordings can show the true performance of your headphones. If you want specific tracks, here are few albums I use:
Pulse by Pink Floyd
Houses of the Holy by Led Zeppelin
Somethin' Else by Cannonball Adderly
Random Access Memory by Daft Punk(Studio Masters Edition)
All of these albums have pretty good dynamic range and master, and I'm very familiar with the tracks, allowing me to compare a specific headphone to my other gears.