17:29:33.285: WASAPI: Device 'SyncMaster-4 (NVIDIA High Definition Audio)' initialized
17:29:33.303: WASAPI: Device 'Microphone (Blue Snowball)' initialized
You've got only two audio devices configured. I'm going to assume the 1st is your default output and the 2nd is your microphone. Assuming the SyncMaster is a monitor or TV, if that's connected to speakers that are in the room with your microphone, that could be causing echo, but that's not the only potential cause.
17:29:32.620: Audio monitoring device:
17:29:32.620: name: Default
17:29:32.620: id: default
You've set your monitoring device to the Default windows audio device. You should not do this. It means that for any sources that are set to "monitor and output" you will create a loop-- you are capturing Windows default audio in OBS, and then OBS is sending that audio back again to the default device. This will cause echoes and/or terrible feedback.
Check the audio mixer at Edit > Advanced Audio Properties.
Note which audio sources/devices are assigned to which Track(s) and which are set to monitor as well as output.
Then look in Settings > Output and see which audio Track (singular) is selected for audio output.
You can record multiple tracks simultaneously.
You can only stream one. So if you have multiple audio sources, but you're only hearing one, it's possible that the device that is missing is not assigned to the track you are streaming.
And if you're hearing echo, it's because either you're sending monitor output to an audio device you are also capturing, or because you have monitoring ON for a source you are already hearing because it's your system default.
If you want more control over audio sources in OBS it can be useful to use Voicemeeter:
https://obsproject.com/forum/resour...nagement-for-1-and-2-pc-streaming-setups.397/
