Favorite song to demo or test drive speakers?

Jan Hammer - "Darkness/Earth in Search of a Sun", and the whole album “First Seven Days”

Steely Dan:  “West of Hollywood”

Bach:  any good recording of “Toccata and Feuge in D Minor”

+1 Jan Hammer/Jeff beck song. Great choice. 
Walk on the Wild Side, Lou Reed. (Background singers!)

Poinciana by Keith Jarrett Trio, Live in Paris (drums first, then the most beautiful sounding piano—great for comparing DACs)

Follow Me Home, Dire Straits (soundstage test for ocean waves, then bongos, drums, then bass and various guitars...and then vocals). This track will mesmerize you on a good system. 

This just reminded me that when I was a kid, a new set of speakers was put to the test by playng Edgar Winter's >> Frankenstein. After all, it did cover a large part of the frequency spectrum, right?

+1 Jan Hammer/Jeff beck song. Great choice. 
Walk on the Wild Side, Lou Reed. (Background singers!)

Poinciana by Keith Jarrett Trio, Live in Paris (drums first, then the most beautiful sounding piano—great for comparing DACs)

Follow Me Home, Dire Straits (soundstage test for ocean waves, then bongos, drums, then bass and various guitars...and then vocals). This track will mesmerize you on a good system.