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LATEST VERSION OF THE DRIVER IS: https://shinywhitebox.com/swb-audio-app
Don't use iShowU Audio Capture on 11.0+. It won't work. Please use the above.
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How does iShowU Instant (or Studio2) capture application audio? This is an often asked topic. Here I try uncover the "secrets" (ok, a little bit dramatic, it's not really secret).
Using a 'virtual' sound driver. What goes in one end comes out the other; then iShowU will route that sound to your speakers so you can hear here.
Note: iShowU Audio Capture itself is just a virtual driver. Being able to "hear" the audio from it requires more support (which iShowU Instant / Studio2 provide). OBS, for example, does not do this.