Matrixiux

I got Logitech G19 Keyboard. It has it's own customisable G Keys, and them keys can run LUA Scripts. I want to make 1 of them button to toggle between my sound output devices.
Sometimes I am using my Logitech G35 USB Headphones (1 device) and sometimes I want to switch to my video card's speakers (2nd device) I was doing way too much research on that, and ended up nowhere... I need some kind of Expert here.

I am asking for a Full working LUA Script for Windows 7.