Are you looking for a free virtual sound card for your Mac or Macbook? If so, you can simply download and install this video converter for Mac. It comes with both free trial and paid versions. You can just download the free version with limited features. Switch from the Convert to the Download mode, you will see a screen like this.
Click Record Video from the upper left section, you will be prompted to install the virtual sound card on your Mac first.
Click Install button, the Mac OS displays the installation blocked notification as following.
This is caused by a new security feature with macOS High Sierra 10.13 and later. Kernel Extensions (KEXT) that are not signed by Apple are no longer automatically installed by default. So we have to allow the installation of third-party KEXTs manually.
Click Open Security Preferences button to open the Security & Privacy window. Then click the Allow button continue.
Once the virtual sound card was installed on your Mac or MacBook, you need to relaunch the Video Converter to complete the update. After that you can make use of the virtual sound card to record internal audio on Mac, record music from internet, etc.
About the video converter
It is a multi-functional video converter. You can find many extra features, such as audio conversion, video downloading, screen recording, DVD burning, ISO burning, video transfer, GIF making, etc.