The SC206-205 is an audio adapter that converts unbalanced audio signals to balanced audio. The converted signals provide better sound quality and greatly reduce noise over long transmission lengths. The unit is passive and may also be used to convert balanced signals to unbalanced signals as well. The SC206-205 is designed to convert unbalanced audio output from computers, DVD players, VCRs, etc. to balanced audio. The SC206-205 possesses superior bandwidth and is perfect for home theaters as well as marketing and sales presentations. The SC206-204 is also a passive device and is designed to convert a standard computer audio output to balanced audio. It has excellent bandwidth and is ideal for most commercial-user applications. Since this unit is a passive device, there is no need for an external power source. Simply make the audio connections and it is ready to go.