isolation transformer box for unbalanced consumer audio line signals
http://www.jensen-transformers.com/as/as001.pdf
http://www.jensen-transformers.com/as/as057.pdf
This service manual includes the the device circuit diagrams.
http://www.rane.com/pdf/old/mp24sch.pdf
for used with long 600 ohm lines which need termination
http://www.jensen-transformers.com/as/as009.pdf
http://www.jensen-transformers.com/as/as080.pdf
8 channel microphone splitter that can inject phantom power to microphone.
http://www.procosound.com/images/Ms82p.pdf
active line level splitter circuit with input and output isolation
http://www.jensen-transformers.com/as/as041.pdf
audio signal isolation transformer
http://www.procosound.com/images/IT1.PDF