REW impedance setup

[groundsound]

Sorry for the Newbie question, but If using a headphone output to the soundcard to measure impedance, is the headphone output from the soundcard looped back into itself? Am having a hard time grasping this setup despite doing a fair amount of reading. Don't want to blow anything up.

 

[John Mulcahy]

The output goes to the sense resistor and the left soundcard input, per the diagram.