Just found this thread searching for a similar answer. So I apologize if you already figured it out.
[strike]You'll need this: http://us.store.creative.com/Dolby-Digital-Live-and-DTS-Connect/M/B006GK76QE.htm[/strike] This doesn't seem to work
If you look at Newegg and search "sound" under the customer reviews for the board, one of the reviewers mentions the software I indicated above. And even if it doesn't work, it's only like $4 (I have yet to buy it because I do not have headphones that support DDL yet...I am waiting on Turtle Beach to release their new headphones and sound processor this year. Hopefully soon).
I have the same board so I have been searching high and low for how to enable virtual surround sound for headphones/headsets.
From how I understand it, you (and the rest of us Asrock Z77 Extreme4) have 3 sound options:
1.) Use the Turtle Beach headset and the Creative DDL and DTS Connect software together.
2.) Upgrade the THX TruStudio software included on the Asrock Z77 Extreme4 drivers CD or online at their website. You would then need to plug your headset directly into the motherboard's onboard sound. The software upgrade can be found here:
http://us.store.creative.com/Sound-Blaster-XFi-MB2-Download-only/M/B006GK73K8.htm
3.) Instead of option 2, buy a cheap sound card such as the PCI Asus Xonar DG (about $27) or the updated PCI-E Asus Xonar DGX (about $40-50). You would then plug your Turtle Beachs into that and use either Dolby Headphone or Dolby Digital Live (I think that it offers both options). I think this is a much better option than #2. Best Option that for sure works
I believe Option #1 should be able to do exactly what you want, but I thought I'd try to explain the other options you do have (from how I understand it).
I hope that helps!