VAC Phi 70 - 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 is achieved with RCA single-ended
sources by using the lower RCA jack adjacent to the XLR input.
The INPUT SELECT switch is set to BALANCED for either the XLR jack or the
lower RCA jack.
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.