Security systems and methods for protecting retail display merchandise from theft are provided. For example, a security system includes a sensor configured to removably engage an input port of an item of merchandise, and a monitoring component configured to wirelessly communicate with the sensor and to removably support the sensor thereon, wherein the monitoring component and the sensor are configured to communicate with one another to determine a proximity of the item of merchandise relative to the monitoring component, wherein the monitoring component and/or the sensor is configured to initiate a security signal when the proximity between the monitoring component and the sensor is not within a predetermined range, and wherein the monitoring component and/or the sensor is configured to initiate a security signal in response to the sensor being removed from the input port of the item of merchandise.