Question about Elgato Game Capture 4K60 Pro MK.2

Hey guys, I just can't figure it out... The installation so far has worked well with the console. The picture is transferred, nicely with 120hz, perfect. However, I have problems with the sound. I want to stream via STLOBS, but I only get sound through when I set the audio output on the console to HDMI, but then my headset no longer works, and voice chat logically no longer works either. They can't be serious, can they? I must be missing something