Cubase

Cubase opens audio in no external editor other than WaveLab, so audio moves between Cubase and HARP as files.

Send Audio to HARP

1. Select the event, and choose Audio > Bounce Selection. Choose Replace, which writes the audio of the event to a new file in the Audio folder of the project, and swaps the event for one that plays it. The original file is left untouched.
2. Drag the new file onto an input track of a model in HARP, and select Process.

Bring the Result Back

Drag the output track from HARP into the Project window, which imports it as a new event at the position where it is dropped.