Systems and methods for shadowing an HDA codec

Systems and methods for "shadowing" a target codec to provide additional features that are not available in the target codec. In one embodiment, an audio amplification system includes a High Definition Audio (HDA) bus, and an HDA controller, a conventional HDA codec and a shadow HDA codec coupled to the HDA bus. The conventional codec receives audio data and commands from the HDA controller via the bus and processes them to generate an output audio signal. The shadow codec snoops the audio data and commands on the HDA bus that are targeted to the conventional codec. The shadow codec processes the snooped audio data and commands to generate a second audio output. The shadow codec does not communicate with the HDA controller and is transparent to the controller. The shadow codec does not request enumeration from the HDA controller and does not receive an address from the HDA controller.