Takes one 6.3mm stereo or two 6.3mm mono plugs on each in- and output
The signal goes from the input to one of the outputs, depending on the switch position
Always use the left channel connector for stereo plugs, leave the right channel open in that case
Dual mono and single stereo conections can be mixed
The audio connectors are NEUTRIK NRJ6HF - I use the -AU version because I can, but the standard version should work just fine
The switch is a C&K PVA2EEH31.7NV2