Focusrite Scarlett 18i8 Manual page 10

Loopback
Loopback allows the user to record audio directly from the computer, such as from apps, web
browsers, or from sites like YouTube. The Scarlett 18i8 uses channels 11 and 12 for loopback.
These are virtual inputs that have no physical counterpart on the audio interface itself.
You will have to enable channels 11 and 12 in audio preferences of whichever DAW you are using,
and then select those channels in your input configuration. Loopback must also be selected
and unmuted in Focusrite Control.
Important Note: You must mute the loopback tracks in your DAW or else you will create terrible
feedback which can damage your ears or equipment. Before playing back your recording,
remember to disarm your track, and go back to Focusrite Control and mute Loopback.
Because of the risk of forgetting to mute/unmute or reconfigure channels for playback please
only do Loopback recording via Headphone monitoring. This means you should either turn off
power to the speakers or mute the speakers in Focusrite Control.
Loopback In Audition
In Reaper, the virtual inputs Channels 11 and 12 will display as Loop 1 and Loop 2 in the audio
channel configurations. Go to Edit→Preferences→Audio Channel Mapping and under Device
Channels, select Loop 1 and Loop 2 by clicking on the pointers at the far right of the menu.
In a new Multitrack session, mute a stereo track to prevent feedback, and arm the
track. Click record and then play the source audio.
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