Sonifex RB-BL4 Dual Stereo Bi-Directional -10/+4 Unbalanced/Balanced Level Matching ConverterThe The RB BL4 is a dual bi directional stereo unit for interfacing domestic or semi pro unbalanced equipment to professional balanced line levels, and vice versa. The four XLR 3 electronically balanced inputs have an impedance of 20kohms bridging and are routed to four unbalanced RCA (phono) outputs with an output impedance of <50ohms. The four RCA unbalanced inputs have an impedance of 20kohms and are routed to four balanced XLR 3 outputs with an