two inputs are available to the mono input channel,via xlr connector{normally for microphone sources} or 3-pole 1/4"'a'gauge jack socket for signals needing a higher input impedance such as keyboards,drum machines,synths or tape machines.both input sockets are permanently active,and may be used simply by plugging the source into the required input.you do not need to unplug anything in the mic socket if you want to use the line input.the ultramic+tm input provides very wide gain control{without the need for a pad},high cmrr and+28dbu input capability.