Hello Tealeaf and giftee and welcome to these forums. You'll find many helpful people here and a lot of useful information. Make sure that you get the excellent User Guide too: -- in Reaper's Preferences, enable the LaunchKey and set its mode to Input AND Control -- on a track, select the LaunchKey as the MIDI Input device (all channels), Arm the track for Recording and check that Input Monitoring is enabled. -- add the ReaSynth plug-in to the track and turn down the track volume level (just in case ;)). Details of all of those steps are in the User Guide and there's a check-list in section 3.40.