VAC Phi 30/30 - Manual (Page 9)

7
INPUT CONNECTORS
XLR connection, balanced or single-ended, are made to the XLR jacks on the
rear panel.
The INPUT SELECT toggle switches 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 jacks on the
rear panel. This is the “direct in” mode.
The INPUT SELECT switches is set to “RCA”
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.