DirectShow video/audio capture gives clicks in Audio Output Mode "Output desktop audio (DirectSound)

[Noormanman]

I have a DekTec SDI card (DTA-2178) which I use to capture SDI audio and video.
Now I can set the audio output mode to "Capture only" and everything works fine. However when I use the audio mode "Output desktop audio (DirectSound)" I will hear clicks in the audio, every half a second, which disappear after a while.
The easy solution is not to use this mode, but I am trying to improve the DekTec DirectShow driver.
Technically, it seems that the DirectShow DirectSound output to the desktop uses rate matching, which is too aggressive the first few minutes.
My question is, who has experience with DirectShow live sources, and has a hint how to solve those clicks? Is it a video/audio source problem, or is it an can OBS Studio setting? I would love to hear some feedback.
And a second question, who needs the "Output desktop audio (DirectSound)" output mode and for what devices? Is it not easier to always use Capture only, and do the audio mixing in OBS Studio?

 

[Harold]

What happens if you use "Capture Only" and instead use audio monitoring in edit - advanced audio properties to listen to the device?

 

[Noormanman]

For Capture Only, audio is good in audio monitoring. The problem only occurs when de input is routed through "Output desktop audio (DirectSound)"

 

[Harold]

Then use the capture only with audio monitoring.
The other options are known to have issues with audio playback in some system configurations