Radial Engineering Highline Stereo - passive line isolator balances the signal to eliminate hum caused by ground loops; linear frequency response from 10 - 70,000 Hz; inputs: 4x 6.3mm jacks (2x thru for looping through the input or 2nd line). Output: 2x male XLR; switchable Gnd/Lift, Thru SUM and XLR SUM; 1:1 transmission with precision-wound Jensen transformer; no external power supply required; dimensions (WxDxH): 84 x 127 x 45 mm