An AudioBox is not needed to record using a SL 24.4.2Ai Mixer. If you are having issues with " Audio Recording Disabled " please double check your PC's Playback and Recording Device Settings. Make sure that all sample rates match, that all exclusive modes are disabled and that any enhancements are also disabled. It is also suggested that you double check to make sure that you are on the latest drivers for the 24.4.2AI and that your FW card is up to spec.