Many people (especially audiophiles and audio engineers) have multiple sound outputs from their computers. Furthermore, they might even have multiple inputs. It is a little tedious to go to the start menu, find sound, switch the device, close out, and then repeat it every few minutes or so. Between RCA, MIDI, and USB, chances are that you will have more than one set of speakers or music makers connected to your computer at any given time. Use AutoHotKey and a little custom script to make switching fast and seamless.