What music do you use to assess your system?


I'm looking for music that will reveal shortcomings or strengths within ones system. Lets list some of our favorite songs that have: good, fluctuating bass lines, songs that have a solid, centerd vocal, songs that are super complex with alot going on, songs that test tone, songs that test inner and micro detail, songs that test how well a speaker can convey dynamic swing, and any other aspects I didn't mention.

Of course I'm not looking for one song that covers all areas, I'm fine with one song only covering one aspect.

When listing songs, please include what we are looking for in that particular song!
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Here's another title which I've used to assess gear- Donald Fagen- The Nightfly.
I love going back and reading old posts by myself to see how my audio hobby has progressed.

I recently got a pair of new speakers and they make everything sound better so there's no need to play a song I've heard 1,000 times to pick out slight differences because everything sounds awesome.

I have found that songs with Piano or classical (large orchestral) music will showcase a systems weakness but I also found that you can asses tone, attack and decay, transient snap, bass articulation, imaging, and frequency extension on many songs.

I have also found that Classical music will showcase dynamic swings and will let you asses if you speakers still sound detailed and impactful at low volumes (whats this called by the way?)

I have also found that one of my old "go to" songs I used to asses my system sounds about the same on most speakers (sounds good) and that there isn't much going on to test a speakers performance.

I've found that complex passages where there are many instruments being played at once are good songs also.

I guess in retrospect, I'm wondering now if its not more important to improve your listening skills and asses your rig on any and all music rather than the 10 songs you've heard 1,000 times...
I like to use the opening of the vinyl LP Genesis, A Trick of the Tale. It has a nice, broad range of notes. Bad, digital listen here: http://www.youtube.com/watch?v=kJIVuinJlsU

B.
I'm such a gear head that I don't actually use music to assess my system. I use many other criteria though, such as; looks, cost, number of knobs and believe it or not weight. I figure the more something weighs the more stuff is in there so it has to sound good. Oh yeah, where you buy a component is also important. 8^)