Precision Power DCX 300.4 - Manual (Page 23)

ADVANCED INSTRUMENTATION INPUT
The Advanced Instrumentation Input has been incorporated from
the legendary
PrecisionPower TM 2500F1 . This circuit completely
isolates the chassis ground from the audio circuit of the amplifier
and reduces noise radiated into your signal cables by up to 40dB.
This is equivalent to a noise reduction of approximately one hundred
times what the noise level would be without this circuitry. It provides
all the benefits of a true balanced line without the need of any
special cables (see diagram below). This type of input works with
any conventional RCA cables.
QBASS
For extra BOOM from your
system, we’ve developed the
QBASS TM bass control circuit.
The QBASS TM control is
located on the end plate
panel, and allows you to add
up to 18dB of boost centered
at 40Hz by rotating the control clockwise.
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