Make sure to use the Avermedia Stream Engine and use 32-bit OBS
I did but very high CPU Usage, even in the Preview Screen without Encoding :(
That has nothing to do with the AVerMedia device, nor with Stream Engine. We're going to have to see your settings.
It'd be best for them to help if you update the original post with logs. Here is how: https://obsproject.com/forum/threads/please-post-a-log-with-your-issue-heres-how.23074/
What are your other settings? We need more than just your CPU preset. Medium is fairly high, by the way. Also, the LGP Stream Engine is fairly inefficient and only works well at 30 FPS, preferably at 720p. The LGP Stream Engine software hasn't been updated since 2013.
Hopefully some Avermedia Dev will read this here ...
I need 50 FPS for high motion.