As an alternative to SoundFlowerBed, you can use a Multi-Output device to get the same functionality.
To do this, in Audio Midi Setup, create a multi-output device, and enable all devices that you want to use. (see Multi-output Device image)
In System preferences>Sound, enable "Show volume in menu bar (Sound preference image)
Use volume menu to select output device (Device selection image)
In Dorico (or any other app for that matter), select Multi-output device in Device setup.
