Why still could record internally without Stereo Mix

[jfhu]

Hi, everyone.
I have a computer (Dell Dimension 5100) with XP Pro installing on it. In the control panel of Recording Control, there is no Stereo Mix options, only Line-in, Microphone, but I can still record the music from WMP, however with the quality degraded gracefully(low volume, noises). Could someone tell me why still I can record the output of sound card without Stereo Mix? P.S.:My sound card is SigmaTel High Definition Audio Codec

Some more information:And I found that when I adjust the volume of Line-in, the volume of my recorded audio file varies correspondingly. So, it seems to relate to the Line-in recording device. But I'm not sure.

 

[CaedenV]

I am a little confused at your question. Are you trying to record a live output stream? Or is the computer recording one and you would rather it not do that?

What software are you recording with?
What source are you trying to record?
Are you trying to mix different sources?
Is this XP Pro or XP64?

 

[jfhu]

I am a little confused at your question. Are you trying to record a live output stream? Or is the computer recording one and you would rather it not do that?

What software are you recording with?
What source are you trying to record?
Are you trying to mix different sources?
Is this XP Pro or XP64?

Sorry about the confusion. What I want to know is why still I can record the sound played by WMP without the Stereo Mix enabled. The software I recording with is the Recorder in Accessory of Windows XP Pro.