How to change Spotify (and other applications) audio output device

Sometimes, when using OBS, I want to be able to redirect some of my applications audio to some different audio outputs. This is so that, when recording the output, I can split the different audio sources and remix them in video editing software afterwards. 

This was something that we used to be able to do per application. Today, however, programmers rely entirely on the OS to provide the correct output speakers. 

There are methods for doing this that could involve using secondary devices (like a phone) and piping the audio into the line-in or a mixing desk. However, not everyone has access to additional devices and cables in order to get this to work.

In Windows 10 it is possible to change the output device for applications on an application by application basis. 

The steps to do this are:

  1. Open Windows Settings By Searching for Sound Settings in Cortana
  2. In the Settings application that opens, search for Sound Mixer Options (searching for "Volume" also appears to work)
  3. Scroll down the list of open applications until you find the one you want, and alter the input and output audio devices as required.