When I first started Dorico and played a sample project, not having installed Halion Sonic SE yet, the DoricoBeep went at me at full volume coming from my Mac’s speakers and almost blew my ears off. Making things worse, since my system audio output was configured to my Scarlett2, my initial instinct of muting the audio through the keyboard didn’t work, and it took me an extra couple of seconds to stop the playback.
(At least, that’s my recollection of the exact steps and setup and what occurred - it was a week ago already so I might have one of the details wrong. Not the audible experience, though )
I suggest either/both lowering the default volume of the DoricoBeep instrument, or taking the system-set audio output as the initial one for Dorico, not the Built-in output. I hope this makes sense.