Keyboard macro to change default audio device

Based off of this article.

1. Download and install AutoHotkey.

2. Open your sound control panel. This can also be done through running mmsys.cpl through the start menu search or the run dialog.

3. Note how far down the list your desired options are. In the following image, the HDMI Output is item 1 and the current default Speakers is item 4.

   

4. Modify the following script. F6 and F7 represent the activation key (F6 and F7) (the * means this hotkey applies even when modifiers such as Ctrl are pressed). The {Down #} command indicates how far down the list to go. From your screenshots, you want {Down 3} for Speakers and {Down 4} for Headset. If you add or remove audio devices, or show/hide disabled items, the number will change.

   *F6::
       Run, mmsys.cpl
       WinWait,Sound
       ControlSend,SysListView321,{Down 3}
       ControlClick,&Set Default
       ControlClick,OK
       return
   
   *F7::
       Run, mmsys.cpl
       WinWait,Sound
       ControlSend,SysListView321,{Down 4}
       ControlClick,&Set Default
       ControlClick,OK
       return
   

5. Run the script. You can set the script to run at startup if you'd like.

The reason I call this a 'hack' is the script actually opens the control panel (a GUI window). Ideally, this could be done through the command line, by specifying the sound device's GUID.

There's apparently a program with a CLI to switch sound devices. You supply the same number in the list, which makes me think it's not much different from the AutoHotkey 'hack' here. In any case, something like AHK would be required to bind it to a hotkey.

Audioswitch (https://github.com/sirWest/AudioSwitch) allows you to quickly change default audio device (with a click on a tray icon), has hotkey support, shows volume levels on click, and allows custom colours for the tray icon to show which device is in use. Plus, it's open source. So if you don't like it, fork off ... (to your heart's delight).

A second answer is Volume2 (https://github.com/irzyxa/Volume2), another free (but not open source) piece of software. You can set hotkeys to change devices. (You can also, as has been pointed out in another answer, change by othermeans, but this was not what OP asked so I didn't get into it.) It has now replaced, for me, AudioSwitch, mostly because it allows more flexible volume adjustments (which again wasn't OP's question).

A third answer is Audio Switcher. http://audioswit.ch/er. It also allows changing on click, and hotkeys. It does not allow volume changing with the mouse, at least in version 1.