Try to move the cables away from anything which might create interferece. Such as your monitor, other speakers, your computer, high powered electro-magnets, etc.

Also I think it is possible for the fans inside your computer to create distortion on the actual sound card (cpu fan does that to my video card ) so if youve got some kind of big vacuum sucker fan in there, probably a good idea to swap it for something a bit more humble.

The other thing which can cause noise is when youve got the volume too high on the speakers and too low on your sound card / mixer (this may not be the case with a digital connection i dunno). Go into the delta control panel and make sure youre running all the outputs through the delta mixer, then make sure all the volumes are correct for your speakers (nominal input?)

hm okay, seems theres not alot i can do then. cables are as far away as possible from things that could disturb. and theres no huge fan in my box.

the static is equally loud even if i put the speaker volume at 0.

guess ill just have to live with it

Ground your PC.

it is grounded, so that shouldnt be the problem. but thx