Hi, I was just at http://www.xiph.org/ogg/vorbis/listen.html
and they had comparisons of the different compression types. The thing I'm intersted in is the different songs this person used to show differences in the compression type. are there cds with mixes of different songs, styles of songs that put speakers to the paces? a good cd to test all the ranges of the speaker with? i have heard all my favorite cds on my spaekers and they sound great, but i'm just wanting to see the abilities and limitations of my speakers a little better

I think movie soundtracks are a good place to start looking, as they often contain a good variety of music.

Other than that, I'd recommend making your own. If you have a computer with a CD burner, then there's nothing stopping you from creating your own variety mix CD.

I've gotten some of my Reference Test Cd from here.
http://www.uhfmag.com/AudiophileStore.html
Opus 3 Cd's are my favorite....specially Test CD 1 which test depth, soundstage ...etc..