A:Answer If you plug in a normal pair of headphones the audio will be stereo in your headphones. With headphones plugged in the built in speakers do not play any sound, only the headphones do. If you are casting to a chrome cast device the audio and video will be sent to the receiver, and you will also get audio through the headphones, or through the internal speakers if no headphones are plugged in. If you are casting I highly recommend using headphones, because there is a slight lag on what is received on chrome cast.
I use regular Bose headphones and it sounds great. And wired headphones will work that have an aux cable. You do not need to buy the special Oculus headphones, that just helps to make it more convenient so the cord doesn’t get in the way.