On my Sony RX100 IV with Cam Link 4K this is what I do:
- Camera tab: Turn Audio Recording On
- Settings tab: HDMI | HDMI Audio Out On
In OBS Studio for the Cam Link 4K source properties:
- Audio Output Mode: Capture audio only (the DirectSound and WaveOut won't work)
- Tick the Use custom audio device checkbox
- Audio Device: Digital Audio Interface (Cam Link 4K)
In the OBS Studio Mixer:
- Advanced Audio Properties: CamLink 4K Monitor and Output; Tracks 1 enabled
- Cam Link 4K Volume Icon Enabled
I don't use the RX100 IV mic though as I use a regular XLR mic. But thats how I get the camera mic to work.