Includes the unit and complete power supply. In excellent physical and working condition. Overview: The audioengine N22 is a desktop amplifier with a headphone amp built in. There are two inputs, stereo RCA and stereo mini-jack, along with RCA preamp outputs and a 3.5mm headphone jack. USB Port: On the back of the amp there is a powered USB output. Its purpose is only to power or charge a USB bus-powered device; for example it will charge an iPod but not control the iPod, and the audio signal is not transferred through the USB port. Audioengine offers wireless adapters (item numbers 772AW1 and 772AW2, sold separately) that can be powered using this port. Inputs: There are two analog inputs, stereo RCAs and a 3.5mm stereo mini-jack, both on the rear panel. The N22 has no input selector switch, so both inputs are live simultaneously; only one should be turned on at a time. Speaker Outputs: The speaker terminals 5-way binding posts; they will accept pin connectors, spade connectors, single and dual banana plugs, and bare wire up to 12 gauge. Two 70" lengths of 16 gauge wire are included (with no connectors). Preamp Output: The variable stereo RCA preamp output can be used to add an external amp, a powered subwoofer, or an audioengine wireless adapter (item numbers 772AW1 and 772AW2, sold separately). Volume Control: The rotary power/volume control is on the front panel. It controls the volume for the speaker level, preamp, and front panel headphone outputs; turn fully counterclockwise to turn the unit off. Headphone Output: A 3.5mm (1/8") headphone jack is on the amp's front panel. The speaker and preamp outputs are automatically muted when headphones are plugged in.