Here are some CDs I always use to audition speakers:
From Australia:
Midnight Oil, Earth and Sun and Moon
Paul Kelly, May, 1992
Nick Cave, The Boatman's Call
Crowded House: Woodface
Alternative/Americana Country:
Dave Matthews, Busted Stuff
Weezer, Weezer (deluxe edition)
Chris Isaak, Baja Sessions
Dave Alvin, King of California
Steve Earle, Jerusalem
Los Lobos: Kiko, and Good Morning Aztlan
Argentina:
Gotan Project: Lunatico
Brazil:
Bebel Gilberto, Tanto Tempo
UK:
Corinne Bailey Rae, Corinne Bailey Rae
Richard Hawley, Coles Corner
Radiohead, OK Computer
PJ Harvey, Stories from the Cities