Software to easily switch between audio output devices

Question

I use headphones and a pair of screen-mounted speakers each for different tasks at various times during the day, and I have them both always plugged in (speakers use HDMI socket, and headphones in front audio plug). What I'd like is a faster and more reliable way to switch audio output between them than the sound properties in the control panel (the way I currently do it).

Requirements:

• Offers some kind of shortcut to switch between audio devices. I'm okay with it being a desktop widget, a tray icon, or a global keyboard shortcut
• Runs on Windows 8.1
• Free or inexpensive (< 10€)

Good to have:

• Keyboard shortcut is customizable. I'd like to put Scroll-lock to good use
• Ability to assign a default output device for each for each stream/application. For example, a video game would automatically output to the headphones, while a music track is directed to the speakers

Answer 1

AutoHotKey

Since there didn't seem to be any applications for that, here is an AutoHotKey script that does the trick. It opens the playback devices window and then simulates the keyboard presses required to switch the default audio device.

#Persistent
#NoEnv 
SendMode Input 

sc046::
Run, mmsys.cpl
WinWait,Sound
ControlSend,SysListView321,{Down}
ControlGet, selectedDevice, List, Focused, SysListView321
Loop, Parse, selectedDevice, %A_Tab%
    if a_index <> 3
        continue
    else 
    {
        if A_LoopField <> Default Device
        {
            ControlClick,&Set Default
            ControlClick,OK
            WinWaitClose
            SoundPlay, *-1
            return
        }
        else
        {
            ControlSend,SysListView321,{Down}
            ControlClick,&Set Default
            ControlClick,OK
            WinWaitClose
            SoundPlay, *-1
            return
    }       
}
#x::ExitApp

Features:

• Maps a customizable global keyboard shortcut to switch default audio devices (Scroll lock in this case)
• Runs on Windows
• Free and open-source

Cons:

• Unable to assign individual streams to output devices

Answer 2

Headphone Speaker Switcher 1.2 (Rainmeter Skin)

Headphone Speaker Switcher is a desktop gadget that allows the user to switch audio output devices with a single click. It is a Rainmeter skin and therefore requires the Rainmeter toolkit to be pre-installed

It works by simply clicking on the name of the desired target device

Features:

• Free and open source
• Runs on Windows
• Is a desktop gadget and therefore easily accessible

Cons:

• Unable to assign individual streams to output devices
• Requires fiddling with the configuration file if you have more than 2 output devices, or if the devices are not in the correct order, though its language is relatively straightforward