Tapemonitor using Playtrough option

I want to listen to the real recorded audio on the active speakers of my desktop PC using Playtroug. (tapemonitor) But the line-in of the PC (bleu) is always active on the Line-out (green). So both direct and playtroug signals are mixed up! And during normal Audacity playback i hear the line-in source also while it is stil running.
Can Someone help me?

If I understand what you’re saying… Turn off Playthrough (“Audio Input Monitoring” on the current Audacity version) OR turn-off Windows Listen To This Device.

Thanks DVDdoug. I think it must be a windows related setting. Without having started Audacity, there is already a redirection to Line out. I am now looking in my sound settings from my IDT high definition menu.

PS. “Listen to this device” was not active.