Best song for immediate impact when presenting or testing?

I agree that you can easily select music for impact that doesn't do much other than show off one or two characteristics of a given piece of equipment.  Like a lot of others here, I have a ton of music that I listen to that gives the whole picture of a system.  Recently I upgraded my entire system and spent two hours listening to hi-res files, SACD, CD and vinyl to be sure that the combination of gear I was considering delivered me to that place where its just the music.  I'm a rock & roll guy so 90% of my collection is just that.  Here's a partial list of the music I used to evaluate my new system:

"Hotel California" from the Eagles - Hell Freezes Over (digital)
"Lines on My Face" from a 40 year old original vinyl pressing of Frampton Comes Alive
"The Chain" from Fleetwood Mac - The Dance (vinyl & digital)
"Squonk" from Genesis - A Trick of the Tail (digital)
"No Quarter" from Led Zeppelin - Celebration Day (digital)
"Gaucho" from Steely Dan - Gaucho (digital)
"On an Island" from David Gilmour - Live in Gdansk (digital)
"Brothers in Arms" from Dire Straits - On the Night (digital)
"Captain Fanstastic & the Brown Dirt Cowboy" from Elton John - Captain Fantastic & the Brown Dirt Cowboy (digital & vinyl)

There is so much more, but you get the drift.

As you can tell, I'm all about live and classic rock.  Can't help that I am a child of the 60's, 70's and 80's.

Whatever you do, remember, its about the music not the gear.  The gear is simply a vehicle.

Little Wing - Stevie Ray Vaughn

I think the more traditional country artists have some of the cleanest recordings around.  For clarity I don't think you can beat the recordings of Randy Travis. The quality of his voice is fantastic.   For classical the Chesky recording of Itzhak Perlman playing Tchaikovsky violin Concerto in D is my personal favorite.  His violin just hangs out in the air in front of you.  For rock my money is on Dire Straits "Your Latest Trick".  I love the way the sax starts out low in the background then moves right in front of you. And finally for bass I have to go with Josh Groban's "Try to Remember".  

Too many to list but the one playing right now; Jennifer Warnes - Joan of Arc. 

James Ingram & Michael McDonald - Yah Mo B There

Bill Withers - Use Me