This is done by simply transfering the audio input for headphone to the microphone.
To set up stereo mix in Windows XP just follow these steps:-
- Open Volume control (2 methods are shown in the given picture).1st is to open it from start>all programs>control panel>sound and audio device and then selecting "advanced volume control" as shown. Other is to open it directly from desktop if it is available.
- Now when volume control is opened just go to options and select properties as shown in pic.
- Then in properties box select mixer device as Realtek and select recording in "adjust volume for" .Then select stereo mix (see pic below).Press OK.
- Now a new box opens up.In this one select the checkbox given under "stereo mix" and adjust the volume as required.(By default microphone is selected in pic below , you select the highlighted one)
Now you are done with the stereo mix. Test it by playing a song and calling a friend on g-talk . Ask him if he can hear the song.
Note:- To revert back to original settings simply select the checkbox under "microphone" instead of "stereo mix" and adjust the volume.