I can't believe I've never taken the time to search YouTube for pieces by Steven Reich. He is one of my favorite composers, and is noted for being a pioneer in the minimalist sound. His tune "Clapping Music" is, in my mind, a masterpiece, as well as, the below song called "Piano Phase." Before you take a listen let me set up how amazingly difficult this song is. It is basically one musician playing two pianos (it's usually played by two musicians), but each hand is playing the tune in a different time signature. For the laymen that may not mean much, but try to imagine banging on a drum with one hand at 4 beats per second and then using the left hand to bang on another drum at 3 beats per second- and maintaining that for entire song. What you'll find is that the song starts to fold and phase in and out of sequence. It's like witnessing a musical battle as your ear tries to decipher the inherent madness of what's going on.