This is the Visaton Stereo amplifier with level controls [VS-7100]

Robust metal housing with two fixing lugs. Can be connected directly to the line out or headhpones socket of a PC audio card, while the input sensitivity is regulated via the level control
Power supply (12 V) is via a mains adapter (not supplied) or the computer's on board power supply
Typical applications: e. g. for multimedia applications. Suitable for use with small loudspeakers with impedances of 4 to 8 Ohms