This module is a two-channel headphone amplifier with two audio inputs with level controls. Input 1 is normalled to Input 2. A common loudness/master knob controls the level with max. output power ~ 2 W per channel (@ 8 Ohm load). 

The inputs and outputs are DC coupled (i.e. also useful for other applications like small loudspeakers, lamps, LEDs, magnets, motors - provided that the power is sufficient) 

technical details

Width: 6HP 

Connections: 
2x Audio input (3,5 mm) 
Audio output (6,3 mm)