Gavotte Model 2 from Jim Fosgate. This is the original surround-sound processor for a car, hand-built in Heber City, Utah. This unit is capable of taking a signal from either 2 or 4 channels of output from your head unit, and fully converting it to surround sound including center channel, left and right front, left and right rear, and subwoofer outputs. Each input and output channel is independently adjustable for level, and the unit has a high-pass and low pass crossover, as well as a bass EQ and adjustable front separation. 

Jim Fosgate is one of the fathers of high-end car audio. He sold his original company, which then became Rockford Fosgate, and then started Fosgate, Inc, which became Fosgate Audionics. This is considered by many to be HIS signature piece.