Mixer/Line In Question - Issue

When using a mixer to the LINE IN  I cannot eliminate an echo when going live with a mic through the mixer. The manual is pretty clear about this when using a mic input, but not clear on how to prevent this with LINE IN.

In this case, you should use MIC instead of line in and enable the "Output to encoders only" option. There's no way to mute the line in the same way, I'm sorry.

Thanks.