I'm trying to use external speakers w L/R Cntr Chnl/Subwoofer w Sound Card DOESN'T WORK...ALSO LOTS OF STATIC TICKING...NEED TICKING TO STOP AND SPEAKERS TO WORK

trying to use external speakers w L/R ,Cntr Chnl & Subwoofer. Using Zalman Tech USB 5.1CH Sound Card #ZM-RSSC V2

First this won't play all of the speakers, dont understnd that to begin with.

MOST IMPORTANT there is a constant Static or Ticking noise that will not go away always ticking in the background.

Need solution to remove ticking noise and if anyone can help get all speakers working even better.

I am open to whatever product needs to be added to solve all of these problems.

Computer is iMac 27" mid 2011 2.7GHz Incel Core i5 OS X 10.9

Thank you in advance for any help anyone can give.