Yamaha DSP-A990 Operation Manual page 19

CONNECTING THE MAIN SPEAKERS TO THIS UNIT
Connect the MAIN speakers to the MAIN speaker output
terminals of this unit. Make sure that the jumper bars between the
PRE OUT and MAIN IN jacks on the rear panel are in place. It is also
possible to use an external power amplifier if more power is desired.
Main speaker Main speaker
In this case, remove the jumper bars and connect the PRE OUT
jacks to the INPUT jacks of a stereo power amplifier with a stereo pin
cable—making sure to connect the left and right channels correctly.
Connect the MAIN speakers to the speaker output terminals of the
power amplifier.
Power amplifier
NOTE: If an external amplifier is used for the main speakers, it is
recommended to use the MAIN speaker terminals of this unit for the
INPUT
rear effect speakers.
Connect the REAR output jacks to the MAIN IN jacks with a pin cord.
This combination is highly upgraded and ideal for the division of
PRE OUT
sound quality, because the rear channel output of the Audio/Video
system is equally important as the center channel.
This unit
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