that manual sure is a jim dandy not one bit of the audio covered. asus never ceases to amaze me and why my ''last'' 3 asus's were my last.
https://dlcdnets.asus.com/pub/ASUS/...5.1244140184.1534870855-1654681230.1534870855
#5 -- headphone/hedset / mic jack
this port allows you to connect amplified speakers or headphones .
you can also use this port to connect your headset or an external mic .
now you hate to think you could use eather a head phone as is or a mic as is, but not combined ? ..lol...
and that's it not a drop more on the audio used and how to or anything ,wow.
funny what few reviews of the 504's don't even review any of the audio outside that its got built in speakers and they speak .
I was looking to see if you could disable the on board mic and see if it will force detect the one you plug in ?
like here its put the same way
On the left side, you get two USB 3.0 Type-A ports in addition to a single USB 2.0 Type-A port, an HDMI output, an Ethernet jack,---- '' and an audio port that you can use for either microphone input or headphone/speaker output...''
https://www.pcmag.com/review/362206/asus-tuf-gaming-fx504g
now I did see one guy use headphones but his used the hdmi port maybe its set to do audio [head /mic/ ] through the hdmi or maybe have to disable it to get it through the 3.5mm port ?