The DTS Test Demo #4 is a great demo disc, especially for $10. For $30 or $40, you can scan ebay and get different demo discs too.
Demo #4 has the DTS logo demo, Eagles - Hotel California, The Haunting, Saving Private Ryan, Sheryl Crow, Roy Orbison, and a couple others. The Eagles and Saving Private Ryan selections are worth the price alone, incredible source material.
We often use this disc when comparing review units and also just to show off our components... :)
-Joel White
Editor
www.CheapHomeTheater.com