How Do I Know What Type Of Source I Have; The Led Meters - D'Amore Engineering A1500.2 Owner's Manual

How do I know what kind of source I have?
Most likely you have an unbalanced source, in which
case no adjustment to the amplifier switches need to be
made. The easiest way to know is to use a digital
volt/ohm meter. With the RCA cables connected to the
source but NOT to the amplifier, measure Ohms from
the RCA outer shell to battery ground.
Unbalanced = 0 to 1000 ohms
Balanced = Over 1000 ohms

The LED meters

The LED meters on this amplifier are kind of special so
we thought they required their own section in the
manual.
Some history - VU meters and commonly called (albeit
incorrectly) "Power Meters" on audio amplifiers have
been around since the beginning of hi-fi audio. They
add a visual element to the music and they offer a rough
idea of how hard an amplifier is being pushed, or more
exactly how close the output signal is to being as big
(loud) as it can be without clipping. These meters are
just AC voltmeters that are calibrated in such a way so
that when the amplifier output voltage is as high as it can
be the meter is at its maximum position.
The problems with traditional meters – First, since they
are just voltmeters they know nothing about what the
impedance of the speakers being driven is, making them
not "power meters" at all. As such, most home audio
power meters are calibrated in Watts @ 8Ω, sometimes
they have additional markings for other impedances.
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