I'm having the same problem, except it's not the Matrix that is to blame. Speakers: Logitech X-540. Card: Sound Blaster Audigy SE. I used to only be able to get the center, but right now I have the two front speakers. The Creative tools I have don't seem to like the 5.1 setting. Whenever I choose it, it never tests for rear, center, or the sub. My card's driver is up-to-date, and I'm on Windows XP Pro. Any assistance would be greatly appreciated.