Superlux HA-3D,Headphone Amp, compact headphone amp with 3 headphone outputs 1/4", XLR left/right input, jack Loop out, Stereo/Loop in (jack and minijack), batterypowered 2x 1,5 Volt or with external powersuplly, fits with all kinds of headphones, hard aluminium housing, 10 - 50.000 Hz, output inpedance 200 Ohms, dimensions: 43 x 94 x 140 mm, weight 0,56 Kg, powersupply optional