This drop down lists allows to select audio input and output devices from the lists of available devices. By default Wave Mapper is selected for both input and output.
Audio Input is used for inputting sound sources into the computer. Both Realtime Recognition and Wave Recording are performed through selected device. You can choose Audio Input device here, but source selection can be made only from the Windows Mixer (Recording Properties).
Audio Output allows to select output audio device.
MIDI Input Professional only selects the device to use for MIDI Recording function. MIDI Recording is available in TrueTone Editor, see the Playback toolbar.
MIDI Output allows to select MIDI out device to playback MIDI notes.
Never Send "Program Change" Command to MIDI Devices may be useful when using some external MIDI synthesizers. This settings blocks all Program Change messages when playing any MIDI data. In most cases you do not need this control.