Ok this is how the problem was solved for my situation:
See Pg.39 of your manual
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Setting the rear output and
subwoofer controller
This unit’s rear output (rear speaker leads output
and RCA rear output) can be used for fullrange
speaker (FULL) or subwoofer (S.W) connection.
If you switch the rear output setting
to S.W, you can connect a rear speaker lead
directly to a subwoofer without using an auxiliary
amp.
Initially, the unit is set for rear full-range speaker
connection (FULL). When rear output is
connected to full r