OK, I see the Line Input on the back of the monitor. Nice monitor, by the way!
Let me confirm that you have tried this using 2 audio cables (3.5mm male to male stereo cables):
Connection 1: Motherboard Green Output ---> Monitor Green Input
Connection 2: Monitor Black Output ---> Titan Speaker Aux Input
Windows Setting: Sound Playback device should be Realtek HD Audio Speakers
If you have not tried this yet then give it a try now, but this configuration may be problematic because the Black Output on your monitor is a headphone output and when anything is plugged into it the Monitor Speakers might be disabled. I believe you may have indicated this already, but I'm just verifying.
If that doesn't work, let me know.
The next thing to try would be a headphone splitter "Y" cable - the kind that allows two people (two headphones ) to listen to the same device. Popular with the kids, I think, but you'll use it this way:
Connection 1: Male end of "Y" ---> Motherboard Green Output
Connection 2: Female Leg 1 of "Y" ---> Monitor Green Input (using Male to Male cable)
Connection 3: Female Leg 2 of "Y" ---> Titan Speaker Aux Input (using Male to Male cable)
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