Many digital audio components cannot be connected (digitally) to one another because different manufacturers use different input/output formats (TosLink¨/Optical or Coax). Audio Authority's Model 977 Series solves the problem by allowing you to convert digital signals from Coax to Optical or vice versa. The 977RPO (Receiver) converts the Optical output of a digital source (DVD or Satellite Receiver) to Coax for connection to Dolby Digital¨ or DTS¨ receivers. The 977TPO (Transmitter) converts a Coax signal to an Optical signal. No matter what type of digital audio, Audio Authority can make it work. AA-KIT Reliably converts digital audio from optical to coaxial format. Power pack and optical cable included. AA-KIT-2 Reliably converts digital audio from coaxial to optical format. Power pack and optical cable included.