Hello.
I am not sure about “Default:” in foobar2000. However, I think it is possible to share the playback device with other applications by making the following settings during WASAPI playback in TuneBrowser.
Click on the “EXCL” indicator in the bottom right corner of the Player View.” It will switch to “SHAR”.
This way, the WASAPI device can operate in shared mode and be shared with other applications.