For you who have trouble enable stereo mixing in Windows 8, especially Toshiba laptop with Conexant audio driver. I recently found a really good source to help me with this problem. We know that stereo mixing is required to record audio from internal sound. Unfortunately, not all sound cards (like mine: conexant) support this feature, especially if you are using Windows Vista, 7 or Windows 8. They don’t give a simple interface and settings like Windows XP.
Most of the problems are actually with the audio card. I am using Toshiba Satellite L 840 with Conexant HD Audio driver, most of Toshiba laptops are built with this sound card. This sound card supports stereo mixing, but it is disabled by default. I don’t understand why most people are obviously confused as well. But don’t worry, we can fix this problem by manipulating the installer file. This is a good source that I found after nearly an hour of Google searching, thanks to Prestativo for sharing their brilliant solution. Solve the problem here!
Another way to enable stereo mixing for Windows 8 is to install a third-party driver, like Stereo Mix Plus. This software can fix the stereo mixing function of the sound card and improve it (it is not free, it will be a good idea to test before purchasing). You can try it, but for me the first solution is enough.