Since folks are talking about test tracks they use for speakers:
Below are the quality tracks I used back before I started building my own speakers; this was 2 decades back. I made a CD to take around to shops & usually left the test CD so the sales people could listen for themselves at their leisure, and hopefully understand my critique of what I listened to. By the time I had figured out which speakers I wanted to buy, we had to spend $9k to replace a roof, which meant the $3-4k I budgeted for speakers was gone. Somehow, I ended up on DIYaudio where dark forces tempted me to 'roll my own'. Over time, I MAY have spent as much building speakers as I would have buying them, but I had WAY more fun! I have given up building now, as 1) our house is overflowing with speakers & SheWhoMustBeObeyed has declared 'enough'; 2) our daughter & other interested parties will not accept any more; 3) after 2 decades of retirement, I no longer have the energy to do more.
Besides the tracks below, I also played a couple items from Benny Goodman's 1938 Carnegie Hall jazz concert. Even a poor system can sound listenable when fed great material, but a truly great system can take a less than wonderful old recording and retrieve enough to showcase a once in a lifetime event that happened before I was born.
1) Jennifer Higdon: Concerto for Orchestra, movement V
2) Sharon Isbin, et al: Journey to the Amazon: Seis por Derecho (Antonio Lauro)
3) Nickel Creek: Ode to a Butterfly
4) Richard Elliot: Crush
5) Mickey Hart: Temple Caves
6) Gottschalk: Le Banjo
7) Woody Phillips: Habanera
8) Dixie Chicks: There's Your Trouble
9) Lara Fabian: Urgent Desire
10) Alison Krauss & Union Station: Crazy Faith
11) Diana Krall: Let's Fall in Love
12) Dave Brubeck Quartet: Blue Ronda a la Turk
13) Airto Moreira & the Gods of Jazz: Nevermind
14) The Hot Club of San Francisco: Gong Oh
15) Ska Cubano: Cumbia En Do Menor
16) Fleetwood Mac: Gypsy
Cheers, Jim