Harman Kardon Sound sitck IIs and apogee Duet. How to connect without blowing stuff up?

First post.  Tried to search got zero hits.

I just picked up an Apogee Duet.  I'M using IT with my Mac Pro Tower, (2 x Quad-Core Intel Xeon
Processor Speed:3.2 GHz ) and thought it might be great to use it to play the audio outpout thourgh my Harman / Kardon sound stick IIs with it's speaker.  The connection currently of the Soundsticks to the back of the Mac Pro Tower is via a 3.5 jack, I believe.

Question: How can I connect the Harman Soundsitcks II to output through the Apogee Duet?

Also, this will not hurt the Duet in anyway, correct?  The Sound Sticks have their own power source just want to make sure I don't destroy either unit.

The out(s) female on the Duet accepts 1/4 male plugs, (if that's the correct term... )  Since the sound sticks go 3.5 jack into the back of the Mac their must be some way to split them out to connect it to L & R in/out on the Duet, correct?

Thanks in advance for any help on this set up connection question.

Best,

Herov