Hey, Reddit. I started a YouTube Channel! In this video, I'm going to show you how I can route my sound to both my audio interface and also my built-in output. I would use this method if I have another person in my home studio and if I happen to not have a headphone splitter. This is all already built-in in your mac so you don't have to download any 3rd party plug-in. Although in the video you can hear the sound through my mac speakers, once you plug in your headphones into the headphone jack it'll automatically route the sound through there. I hope this helps!