Professional amplifier Untested last time was working ,like an year ago AUX IN — 2-channel audio input (Left/Right) AUX OUT — 2-channel audio output Volume control Bass control Treble control AC LINE INLET — standard IEC mains connection MAINS ON/OFF switch 230V CE marking A separate small control box with: Volume Headphones Reverb Power indicator The combination of AUX IN/AUX OUT, volume, bass and treble is typical of an amplifier intended to be integrated into a larger audio system. Similar amplifier panels are used in electronic/digital-piano systems