As far as I am aware you will not accomplish this without a little bit of programming or finding a custom app that someone else has created to do this. http://blog.hemp-society.de/2012/12/shortcut-change-windows-audio-settings.html contains information on a command line utility that will allow you to create a shortcut to do what you are looking for
In particular look on the blog where they go into detail regarding the following options:
changeappvolume [Process] [volume level] {Device Name/Index}
They give you examples on how to make a shortcut to call the program using the above parameters to do exactly what you are after. As I've not tried this before I'm not sure how well it works, but if you are having some trouble with the scripting program I am sure myself or others would be able to help.
Incase something happens to the above blog, the location of the actual utility is here http://www.nirsoft.net/utils/nircmd2.html#using