Check out this Dolby Digital test i stumbled upon on the net. It's designed to test 5.1 systems, but i tried running it on just two relatively high-end front speakers. I almost fell off my chair when i heard his voice behind my head even though my speakers are in front of me. Damn, now that's cool! Not sure if this will work as well on lower end speakers, but give it a try anyway, and let me know if it works. For me, it sounds as if he's standing just behind my left or right shoulder, depending on the test - that's on Paradigm Monitor 7 v2 speakers. The file inside the zip is a VOB - original, uncompressed, straight off the DVD. You can listen to it in PowerDVD. Download.
