Cerwin Vega 4 Channel Line level Converter.
The SLMLOC is designed to convert (2) channels of speaker-level audio into (2) channels of line-level audio.
This allows for the installation of line-level products such as amplifiers, EQs, and crossovers on systems that do not have RCA line-level outputs.
In addition, this device will also detect the presence of an audio signal and then generate a +12v output that can be used to turn on an aftermarket amplifier.