Sonifex Redbox RB-UL4 Quad Stereo Unbalanced to Balanced Converter. Professionally Refurbished & Tested Products. IT Equipment at Affordable Prices. Sonifex Redbox RB-UL4 Quad Stereo Unbalanced to Balanced Converter – No Fuse. The RB-UL4 is a 1U rack-mount quad stereo unit for interfacing domestic or semi-professional unbalanced equipment to professional balanced line levels. All connections are […]... Read More