Looking for a device that will get me true Dolby Digital 5.1/7.1 on PC with my turtle beach X41

I originally purchased my turtle beach x41 headset for my xbox 360. I want to use it on my PC but I don’t have a sound card with optical out. The only way I can get real surround sound out of my PC is if I use the HDMI port on my video card, it works great if I hook it up to my receiver in the living room. I purchased an Audio Advantage Micro II online thinking I would get true 5.1 because it has an optical adapter but it just makes MY pc think it’s a surround sound device in windows. Basically no matter what settings I pick I only get stereo sound for the most part. The mode that the Audio advantage supports is call spdif.

So basically I just want to know if there’s any device out there that I can use to convert my HDMI signal into optical with real surround sound or maybe another usb sound card device with optical out that will give me real surround sound? I found a few converters online but I’m not to familiar with sound equipment and I don’t want to get burned again.

This is one of them, kinda expensive though. Will this work for what I want and is there anything out there that will do the same thing but cheaper?