Aurora Audio GTM822-2GN - Manual (Page 15)

Connecting an expansion unit to the master unit :-
When connector expansion units to each other, or from an expansion unit into
the master unit, the signal comes from the male 9 pin D sub connector on the
expansion unit into the female 9 pin D sub on the master or slave unit.
As there seems to be no standard thread length on D sub retaining screws, you
may need to add washers to the screw if it is found to “bottom” into the
threaded nut without fully securing the connector.
Addendum #3 :- Connecting to unbalanced devices
All audio paths entering or exiting the GTM822 (except the monitor headphone
jacks) are balanced. Balanced circuitry is used in professional audio because of
the noise canceling it provides on long cable runs, especially cables that run
alongside ac power cables whose magnetic fields can be induced into the audio
cables. Unbalanced cabling does not provide this protection.
When connecting to unbalanced equipment, special care has to be taken to
avoid ground loops because the ground is part of the signal path... not the case
with balanced wiring.
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