The Ui12 also features four XLR combo mic/line inputs, four XLR mic inputs, two channels of Hi- Z/instrument inputs, as well as a stereo RCA line input. A 2-channel USB media player is included, along with two balanced XLR Aux outputs, two quarter-inch headphone outputs with level control, plus balanced stereo XLR and quarter-inch main outputs. Two-channel USB audio playback is compatible with MP3, WAV and AIFF formats.