The speakers are connected in "2. Speaker Connection" of the Setup Wizard but if you did not use or cancelled the Setup Wizard, connect the speakers as shown below.
For details, see the included CD-ROM (Owner's manual).
5.1-channel
This unit
RCA
RCA
RCA
RCA
RCA
XLR
XLR
XLR
XLR
XLR
SPEAKERS
SPEAKERS
SPEAKERS
SPEAKERS
SPEAKERS
FL
SW
SL
Switch the output voltage with the output level selector according to the connected power amplifier.