This applies to the Scarlett 2i4

If you notice the unbalanced (RCA) line outputs 3 and 4 are louder than outputs 1 and 2 this may be due to the position of the monitor dial on the front of your Scarlett 2i4.

The volume for balanced and unbalanced outputs 1 and 2 are controlled by the monitor dial on the front of your 2i4. Therefore, if you're experiencing less signal from outputs 1 and 2 than 3 and 4, make sure that your monitor volume is set to maximum. This ensures both sets of unbalanced outputs are sending equal volume levels to the two channels on your external mixer.

This is essential when using your 2i4 for DJ'ing, as having unequal input volumes could cause uneven levels when cross-fading from track to track.