The Radial StageBug SB-5W (order no. R800 0155) is a passive stereo direct box built into a wall plate that fits a standard North American single-gang electrical box. AV integrators install it in meeting rooms, lecture venues, classrooms, churches and convention centres so users can plug a laptop, phone, tablet or CD player straight into the installed PA system. The front has a 3.5 mm stereo TRS input and a pair of RCA inputs (plugging into the 3.5 mm jack disables the RCAs) plus a level control. Inside, dual transformers convert the unbalanced source to a low-impedance balanced mic-level signal and remove hum and buzz from ground loops, which Radial says can feed a PA up to 100 m away. A mono switch sums left and right to save mixer channels, and a recessed ground-lift switch helps further with noise. Outputs are balanced left and right on screw terminals with tie-wrap slots, and the steel enclosure shields against interference. It is completely passive, so no power is needed.