7Audio ConnectionsAlways disconnect the AC cord to your A 31 before making or changing any input,output or trigger wire connections. Inserting or removing an input or output cable while theA 31 is turned on can result in a blast of sound that can damage your loudspeakers. Makesure there is no strain or tension on any cables that could cause them to pull loose.Audio Input ConnectionsBalanced XLR Input JacksBalanced connections will give you the best sound. If your surround sound preamplifier hasbalanced XLR output jacks, we recommend that you connect them to these inputs. Refer tothe Balanced and Unbalanced Lines in the Technically Speaking section for additionalinformation about why we recommend using balanced lines.Unbalanced RCA Input JacksUse these inputs if your surround sound preamplifier doesn’t have balanced outputconnections or if you simply prefer to use unbalanced connections.Balanced/Unbalanced Selector SwitchesPlace the switch in the position for the input type you will be using.Note: The Balanced/Unbalanced switches are not input selectors. Theirfunction is to optimize the s/n ratio for each type of input. You shouldnot connect both the Balanced and Unbalanced jacks at the same timewith the expectation of switching between to different signals.Balanced XLR Pin ConfigurationThe balanced inputs of the A 31 use XLR jacks that conform to theindustry standard of:Pin 1: Ground Pin 2: Positive (+) Pin 3: Negative (–).