A controller for use with laptop and notebook digital computers for reproducing compressed digital audio and video files. The controller includes a drive interface for traversing and accessing data stored on a drive of a computer system. Function keys or a remote controller permit users to access drives containing desired data. The selected data is read from the drive. A decoder circuit parses the data into audio data and video data and decodes each set of data to generate a decoded audio data stream or video data stream. The audio data stream can be converted to an analog signal by the controller, or sent to an external ADC of the computer system. Advantageously, the controller operates when the computer system is in an inactive state, for example in power saving mode or OFF, and operates in passthrough or bypass mode when the computer system is ON or active.