Pioneer VSX-709RDS - Manual (Page 11)

Connecting Your Equipment
11
En
Set up
DVD 5.1 Channel Components
In some cases, you may need an external decoder to play special DVD discs and the like. If you find you need an
external decoder, hook one up as shown below. For most people this component is unnecessary. (See p.40)
Components equipped with 5.1
channel analog output jacks
VSX-709RDS
The 5.1 channel input can only be used
when DVD 5.1 CH is selected.