B650pg lightning Audio output issues

So audio out from the line in port is what you are after? I am afraid the only
way I know to do that outside of using Realtek's control panel (and even that only
with certain older versions) is to set the speaker output to quadrophonic or 5.1
and that isn't what you are after.

If your front panel audio is connected then you could use the front panel headphone
jack for your DAC then through your headphones. Unfortunately that board doesn't
have a rear line out so it requires reassigning jacks, usually done through
the control panel of the audio codec provider (realtek in this case).

You can try download the Realtek audio drivers and physically install them (setup.exe)
from within the driver's extracted folder rather than pointing windows to the
driver directly. Then open the realtek control panel and see if it gives you
options to change the jack assignments. It must have been set up this way before
if you were using the blue jack.

Yeah, it sounds like the "autosense" got messed up. Maybe try connecting the speakers
to the blue jack and your DAC to the green one, see if it senses the speakers are
not a microphone or input device.

You may have to do some version jumping to find the driver/control panel that
will do what you need. This has been a real pain for a long time. I had similar
issues with an ITX recording rig I built a few years back. In the end I think
I tried 12 different driver and control panel versions before finally giving
up and installing a dedicated sound card in the PCIe x1 slot. Ironically, the stupid
auto sense started working after I had forked out for a pro audio card....