Twin Stereo Balanced/Unbalanced Bi-directional Audio Converter - 

The Signature UBBU4 is a broadcast specification stereo unbalanced to balanced, and balanced to unbalanced analog audio interface that is equally suitable for professional & home studio use. Its primary job is to interface domestic type audio outputs (unbalanced) to the balanced audio inputs on broadcast and professional audio equipment while simultaneously connecting balanced outputs from professional equipment to the unbalanced inputs on domestic products. As well as providing the balancing interface the UBBU4 also provides variable gain to allow the 4x connected pieces of equipment to match audio levels. 4x Stereo circuits can both work as dual mono. All 4x inputs are electronically isolated with RF filters to prevent extraneous signals, and fed via multi-turn preset gain controls on the rear panel to their outputs.