This unit is equipped with two sets of speaker terminals (SPEAKER SYSTEMS A and B). One set of speakers can be connected to each set of terminals, and a total of two sets of speakers can be connected.
The same signal is output from the SPEAKER SYSTEMS A and B terminals.
When only one set of speakers is to be connected, use either the SPEAKER SYSTEMS A or B terminals.
You can use the SPEAKERS button on this unit to set which speaker terminals are to be used to output audio. Set according to the speakers connected to this unit. link