This command allows selection of one sound input device and one sound output device from the sound devices currently installed under Windows. It is possible to have several sound cards and drivers installed in a system; this is where you select which ones Vox Studio should use. Vox Studio also shows you the capabilities of your sound card and driver here; this is useful for diagnostics. You can individually select which device to use for input and which for output.
You will not be able to record or play any file with Vox Studio until you have selected an installed sound input and output device. You can, however, use Vox Studio to do conversions only, without an input or output sound device.
If you have the Microsoft Sound Mapper installed (it is just software usually installed by default with Windows sound support) it may be a good idea to select it because Sound Mapper allows you to play 16-bit files even if your sound card is only an 8-bit card. Naturally, you will obtain better results with a real 16-bit sound card. You can also play stereo files on mono systems. Vox Studio can play and accept stereo input files but, of course, always generates mono files for telephony purposes. The Sound Mapper also sometimes allows using sampling frequencies normally not offered by your sound device. You may then be able to work at sample rates that your card's hardware/driver cannot support directly. To see if you have the Sound Mapper installed simply click on the drop down listbox in the "Device" frame, all available devices will show.