Abbreviation for Audio MIDI Setup. Apple Computer’s audio and MIDI operating system, which is a component of Mac OS X. AMS consists of two parts. The first allows you to configure the drivers for audio devices connected to the computer, including defining the sample rate and bit depth. The second section provides configuration information for any MIDI devices (internal or external) used. AMS replaces Opcode Systems’ OMS (Open Music System) and MOTU‘s FreeMIDI, which were earlier Mac-based MIDI configuration utilities.