A passive cable adaptor for connecting a data source device with a display device is described. The adaptor has a packet-based interface connector at one end, the connector having a positive main link pin, a negative main link pin, a positive auxiliary channel pin, and a negative auxiliary channel pin. Also at the same end is a serial interface connector, such as a serial interface connector. At the other end is an upgraded serial interface connector (e.g., enhanced serial interface) connector having high-speed transmission pins, high-speed receiving pins, and a ground pin, wherein multimedia content is transmitted over the cable adaptor and electrical power is supplied over the cable adaptor simultaneously.