Linn C4100B (Chakra) Connection of XLR/Cannon Input

A friend of mine bought this 4-Ch power amplifier in balanced mode - go to
Linn Chakra - Manual - Power Amplifier - HiFi Engine
AV-Magazin: Die neuen Chakra-Endstufen von Linn

The seller told him that the function of the 3 XLR pins of the input connectors is not as usual known (1: GND 2: "+" 3: "-") - go to
XLR connector - Wikipedia
under "Three Pin Audio Use"

Unfortunately the associated owner's manual don't mentioned the deviant function - go to
C4100b; C5100b; C6100b - Linn CHAKRA C 2100 Owner's Manual [Page 19]

Who know the exact function of all pins on this power amp model from Linn ?

Thank you very much for this advice.
Maybe one of the members can upload the schematic diagram.
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