Cannot Add "Stero Mix" to Recording Devices

I couldn't find my answer in a previous thread, so hopefully someone can help me here. First off I'm using Parallels Desktop 9 with Mac (OS X Mavericks) as my hosting machine and Windows 7 as my virtual. I'm using a Windows-only screen recorder and need to record the internal audio. I've found through other threads I need to set my recording device to "Stereo Mix" but the only thing I have available to select is "Microphone (Parallels Audio Controller". Can anyone help me in adding "stereo Mix" or the equivalent to my recording devices? Thanks!