Griffin FireWave Teardown
FireWave uses the FireWire (IEEE 1394) port of the Mac as an audio output to its Dolby Digital sound processing hardware, effectively acting as an external soundcard.
Griffin Technology's product website explains that FireWave uses the Dolby processors to allow the user to connect a 5.1 surround sound system. Speakers are then connected directly to FireWave's speaker terminals (three female 1/8" stereo connectors). Many different sound setups and configurations are possible, using a combination of Griffin's included FireWave software and Apple's "Audio MIDI Setup" utility.