I just listen to the songs I like, there's no point listening to reference songs and testing them because I don't know what to test for lol. If the songs I like sound good, then I'm happy with it.

Also cheat song, but the 1994 Hell Freezes Over version of Hotel California sounds so nice on every pair of headphones. It's decent for testing because the first 2 minutes have a thumping bass beat and high note guitars, but it's just a song that will make you appreciate your headphones in general