Audacity’s WASAPI Loopback
Don’t have a Stereo Mix option? Many newer PC's don't. Audacity has a useful feature that will can record the audio coming out of your computer. This takes advantage of something Microsoft added in Windows Vista, and it’ll also function in Windows 7, 8, 8.1, and 10. It helps make up for the lack of a Stereo Mix option on modern Windows PCs.
In Audacity, choose the “Windows WASAPI” audio host and then an appropriate loopback device — for example, “Speakers (loopback)” or “Headphones (loopback).”
Click the Record button to start recording the audio in Audacity, and click Stop when you’re done. Because you’re using Audacity, you can easily trim and edit the sound file when you’re done.
WASAPI loopback has an advantage over stereo mix or similar inputs provided by the soundcard because the capture is entirely digital
