Record Playbacked Audio from soundcard main out

Does anyone know, how i could directly record a playbacked audiosignal from the soundcard main out into wavelab?
For example a signal from a played video or something…
I cannot select my main-out channels from my TC Studiokonnekt48 as signal source.
Only the inputs are available.
please help

A common used method is to physically connect sound card output to input. Take care to disable monitoring, or you’ll be creating a feedback loop.