mediam Hiss noise with Audigy 2 ZS!!!!

hay guys i recenly bought a new system with a Audigy 2 ZS sound card and its awsome but there is a really weird thing happaning here when the sound it set to 5.1,4.0,2.1 it makes a hiss noise and i muted allmost everything and fiddled around the the options and still i couldent make the hiss go away!
iam useing a abit m/b Win XP Pro SP2 and the Stock CD Drivers does anyone have a clue whats happaning here?

Ps. no hiss with Headphone setup!

I would love an answer to this.... windows xp pro sp2, audigy zs 2 platinum ... terrible hissing in the background. This was a system I built for a family member years ago, and it recently found its way back to me. None of the creative aps were working which led me to update the drivers, and the problem began. it appears to have something to do with driver combatibility issues, and I've read about the logitech problems, butI'm not running any logitech peripherals or software. I've uninstalled - reinstalled the hardware multiple times and tried every driver ever made - including the latest beta - with no luck. ughhh i want my speakers back