This vintage system selector is for bringing all connections to the front
AKAI PU300 from 1970's
This is for serious rack system builders.
 
If you fit it to anyrack system , you can bring all connections to the front, then connect them the way you like from front side.use supplied cables for connection,
 
16 kind of inputs, from sources, two out puts  for 2  amplifiers, and 3 speaker system can be connected to  that 2 amplifiers .
All can be selected from connecting cables from front.master volume controller as well.
There are no electronics inside.its passive device.
 
This is very old item, over 50 years old.its rare item from Akai japan.