Select Audio Output Via Command Line

Does anyone know how I can select my audio output via the command line? I'm frequently switching between using my monitors inbuilt speakers and a USB audio interface and I'm finding it laborious to navigiggerate graphically through the settings in GNOME to do so.

What I'd like to do is set up a couple of bash aliases and do it in my terminal.

What's the best way for me to do that?

Many thanks