Balanced; Typical Input Setup - B&K ST1400 Series II User Manual

Balanced -

XLR type connectors accept line input from the preamplifier's balanced
output connectors. There are two input connectors, one for each
channel, that may be used to connect the amplifier to the preamplifier.
Balanced cable connector
Operation - For balanced operation, ensure the balanced switch between the
balanced inputs on the rear of the amplifier is in the 'on' (in) position.
Here is a typical input setup:
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