The Rolls MB15b ProMatch converts consumer level stereo RCA signals to balanced XLR professional line level, and vice versa. One side of the unit has two XLR inputs and stereo RCA outputs. The other side has stereo RCA inputs and two XLR outputs. Each side has stereo level controls, and an LED indicates that power is applied to the unit. It can also act as a balanced XLR line level control. By adding a stereo pair jumper between the four RCA jacks (connecting ins to outs), the two level controls may be inserted into any balanced XLR line.Rolls MB15b Features:Stereo Direct BoxStereo RCA to stereo XLRStereo Level control for each channelWorks as stereo balanced line level control1/8″ Headphone level to line level adaptorRolls MB15b Specifications:Max Out: Balanced: +18 dB, Unbalanced: +12 dBMax In: Balanced: +22 dB, Unbalanced: +22 dB Input Impedance: RCA : 100k Ohm, XLR: 10 k Ohm, 1/8″ stereo: 10k OhmOutput Impedance: RCA: 100 Ohm, XLR: 100 Ohm balancedNoise Floor: -88 dBGain: +4 dB In: -8 dB, -10 dB In: + 20 dBTHD: .003%Power: 12 VDC adapter (center negative)