Roland CPM-300 Owner's Manual page 11

Connecting an External Effects Processor or Equalizer
Connect effects processors, equalizers, and other such equipment using the following Jacks.
@SEND/RETURN Jack
Use these jacks when connecting an effects processor to add effects to the source sound.
* This also can be used as an auxiliary input. Mono input is possible by connecting only to the L input.
@MIXER OUT/ AMP IN Jack
Use these jacks when connecting devices such as equalizers and compressor/limiters, which alter the sound input
to compensate for acoustic and other sonic characteristics. When cables are connected to the AMP IN jacks, the
mixer and amplifier sections are separated, and the signal from the mixer section is isolated.
Effects processor to add effects to Equalizers and compressor/imiters, whicn alter
the source sound the sound input to compensate for acoustic and
other sonic characteristics
<MIXER OUT/AMP IN Jack>
In addition to their use in connecting devices such as equalizers and compressor/limiters, the
MIXER OUT/AMP IN jacks can also be used in the following circumstances
@When volume levels greater than the CPM-300's internal power amp can provide are needed,
connect to an auxiliary power amp and speakers > Connect to MIXER OUT jacks (refer to the
figure below).
@When you want to use the CPM-300's power amp only — Connect to AMP IN Jack
Just as with the CPM-300's mixer signal, the amplifier's built-in limiter circuit works to prevent
the signal input from the AMP IN jacks from causing distortion and speaker damage.
<Using Additional Power Amps and Speakers>
The output from the MIXER OUT jacks can be sent to a separate power amp.
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