Hi @kevlatus - you currently have to hack the source to modify the default audio driver.
In the upcoming beta, you’ll be able to do this via a settings file which will be much easier - hopefully that will be out next week some time. I’m currently re-plumbing the entire MIDI system and am almost finished with that.
In the meantime, if you’re happy editing the source directly you could try this: https://github.com/samaaron/sonic-pi/issues/1881#issuecomment-386576806