SoundSwitch

SoundSwitch is a utility that will let you define a hot key to switch between playback devices.
Most sound cards have several available playback devices (such as Speakers, Headphones or Digital Audio).

Windows lets you change your preferred playback device, by right clicking on the sound icon in the lower right corner of your screen, and choosing the "Playback Devices" option. But it is a lot more comfortable to be able to select a hot key to switch between playback devices.

Normally, the playback devices are numbered from number 0. You can view the available playback devices by entering in the Playback Devices option. Then, you can enter into the Settings option of this program, add the numbers of the devices that you want to add, and enter the hot key that you want to use to switch between devices.

And that is all you will need to do to configure the program. From that moment on, when the program is running, you will be able to switch between the available playback devices just entering the hot key that you have chosen. You can configure this program to run on every startup.