Welcome to the Reaper Forums!
In case you haven't already found them, make sure to check out the User Guide (
https://www.reaper.fm/userguide.php) and Videos section (
https://www.reaper.fm/videos.php) in general.
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1) After selecting the Focusrite ASIO driver, make sure that the input and output range is set correctly in Reaper's Preferences, first.
2) Then check the following Track settings:
- Correct Audio Input selected
- Record Arm Button enabled
- Input Monitoring Button enabled (in case you don't use the Direct Monitoring feature on the 2i4 itself)
More info here:
- Focusrite Reaper Setup Guide:
https://support.focusrite.com/hc/en-...er-setup-guide
- Recording Audio:
www.reaper.fm/videos.php#iLC1HjLXLd0
As a side note:
When using the Focusrite ASIO driver, make sure that your headphones/speakers are connected directly to the 2i4.
And that the appropriate Focusrite ASIO driver is installed for your 2i4 model generation (1st or 2nd gen).