VAC Phi 220 - Manual (Page 9)

7
INPUT CONNECTORS
XLR connection, balanced or single-ended, are made to the XLR jack on the
rear panel.
The INPUT SELECT toggle switch is set to the BALANCED position.
The XLR connection follows the EIA “pin 2 hot” polarity convention.
RCA (single ended) connection normally is made to the RCA jack on the rear
panel. This is the “direct in” mode.
The INPUT SELECT switch is set to “RCA”
In many systems a lower noise floor and better sound is achieved with RCA
single-ended sources by using the XLR input via the lower RCA jack and the
switch set to BALANCED position.
Note: the photo shows an earlier version that required an RCA to XLR
adapter. Later units have both an XLR connector and a lower RCA jack.
The balanced input also has a switch that allows pin 1 to float or be connected to the chassis. Set
this switch for best sound/lowest noise in your system.
NOTE: Do not remove and connect input cables or speaker cables while is amplifier is running.
Doing so risks damage to your loudspeakers or the amplifier.
Do not operate the amplifier without a loudspeaker or load resistor attached.