Adding Stereo Mix on Windows 7?

I'm trying to get Stereo mix enabled in Windows 7 to play Call of Duty 4 Online. I've tried everything that I've been told, plugging in headphones, updating drivers, downloading new drivers etc... but I always get the iw3mp.exe error when I try to start the game. I'm almost 100% sure it's because I don't have Stereo Mix on my sound settings. How can I download this? Please help I'm really frustrated.

PS I also have Windows 7 Home Premium 64-Bit.

 

For some time now I have been trying to use the old "stereo mix" or "what u hear" I had on my old PC with XP. I built a new rig, got a new sound card and put Windows Seven on it but could not find Stereo Mix. So I started using an external audio cable to use "Line In" as my recording device and it works BUT when I'm recording and there is no audio there is a loud hissing sound and it makes it not worth while.

So after messing around for a while I found out that my sound card just does not have that option so this is what I did next and where I am stumped.
I even tried to find a bunch of different registry value to enable (from YouTube tutorials) but I just don't have them because it might just be a Dell thing. Anyways they were:
DigitalStereoMix
DigitalInputMonitor
EnableInputMonitor

 

simple solution here. go to your recording devices tab under sound. then right click the white space under your default audio device, select show disabled devices....that should show you the stereo mix, then you can enable it and bam, you got it.

 

Stereo Mix is part of the particular audio driver that comes with your audio card. (And no, you can't just use some other driver if your driver doesn't include Stereo Mix. The driver is written to interface to the particular hardware on your card.)

Since Stereo Mix can be used to steal music, and since the audio card manufacturers are afraid of being sued by the music industry, more and more of them are eliminating Stereo Mix. If you absolutely have to have it, either find a current card that still has it, or roll back to an older card that does. (Or, if you can, write your own driver. If the card if full duplex, Stereo Mix is kind of trivial.)

Or you can plug a patch cord from Line Out to Line In and use Line In as your recording source. It works with some cards.

 

If your computer hardware is so well, such as high quality of sound card ETC, you just download virtual audio streaming to record sound. According to my experience, Virtual Audio Streaming is a good choice for you, Virtual Audio Streaming as a virtual audio driver to support Stereo Mix feature which Microsoft and Audacity have ignored without any explanation.
http://www.virtualaudiostreaming.net/use-vas-driver-to-fix-audacity-recording.html
you can download it to have a look.

 

According ro what ELLA77said, I download Virtual Audio Streaming and install this software. To my surprise, there is a lot of fantastic features far more than Stereo mix. So I come back and recommend Virtual Audio Streaming to you. In fact, it is really worthwhile for you to explore this software.
Virtual Audio Streaming Visit page:
http://www.virtualaudiostreaming.net/