A:Answer Hey 2swat,
Never any dumb questions...
Yes, the computer audio and the mic sound will both play back through the G-Track's headphone jack. When you plug it in, you have to go into your recording software's Preferences and choose the "G-Track Pro" for both Recording & Playback, then ensure you have your headphones plugged into the G-Track Pro headphone jack and NOT the computer's.
Hope that helps!
-Bobby