How to connect audio setup to the motherboard

[Senglide]

Hi!

My current audio setup contains 2 internally amplified speakers that get their audio signal from a small mixer. I have two inputs on this mixer: one for my laptop and one for my dj controller. I am planning to build a computer and wish to keep this setup, only switching the laptop with the new pc. I would like to connect the pc to the mixer trough the back of the motherboard, so I can use the front audio headphone jack for my headphones.
I'm making this post because I have little knowledge of how all the audio outputs on the back of a motherboard work. There are several outputs, and I would like to know which one I'm supposed to use to connect to my mixer. The motherboard I'll be using is the Gigabyte AX 370 Aurus gaming K5 and has a 7.1 surround connection. All the in- and outputs on the mixer are unbalanced 6.3mm jacks (one left and one right channel for every in- / output).
Can anybody help? Thanks! 

[anothertom]

Presumably you have a 3.5mm to two 1/4'' jacks going from your laptop into the mixer already, and you want to just reuse this cable.

 

If we look at this picture of the back of your motherboard, looking at the audio stack on the right. From top left clockwise you have Centre/Sub, Line in, Line out, Mic in, Optical digital out, rear L/R. Since you're only using a stereo setup user the Line Out jack (right hand side in the middle).

[Senglide]

Wow I didn't even realize those were jack outputs. I always thought it were rca connectors... Now it makes sense that one of the outputs can carry a stereo signal. Thanks for making that clear!