Interfered with AirPlay

After switching from an old Macbook (2006) to a MBP I was looking for an alterative to AudioSource, since they didn’t upgrade their app to work on new computers. I found Audio Switcher and thought that it came pretty close. For about three weeks now I am trying to get the AirPlay mirroring working from my MBP to the Apple TV. Just right now I realized that Audio Switcher was the problem. In the meanwhile I also found out that I can do the same thing this app does simply when I option click on the Audio icaon in the menubar.

edfunk about AudioSwitcher, v2.24.942