sound issue with ATV and computer monitor

I am hoping to find a solution here, as i thought i figured out but struck out.

my TV recently crashed on me and while i wait to replace it, i decided to connect an old LCD computer monitor to my ATV and DirectTV boxes in hopes of using them. Connecting via HDMI to DVI cable and I get picture great on both but no sound. Did a little research and found that R/L stereo audio to digital coax & optical converter like this http://www.monoprice.com/Product?p_id=8127&seq=1&format=2 would work. connected it all up and plugged in 2 speakers to the cable and still got no sound.

Any idea what i am doing wrong or need to replace/pick up instead?

thanks!