Hello, thank you for reaching out to Microsoft Q&A.
- When the Rodecaster Duo and headset are disconnected, and only the soundbar is connected to the PC via the aux cable, do you get sound?
- Can you check the Windows Sound Settings to see if the soundbar (Speakers/Headphones – Realtek or similar) is listed as the default playback device?
If the issue appeared recently, try doing a system restore process and see if it helps.
- Click Windows + R key, type rstrui.exe, and click ok.
- Select the date/time you would like to restore your computer.
- Click Next > Finish to complete the restoration.
- Unplug all of your audio devices and plug them in again.
- Test your audio output.
Let me know how it goes.