Increases the line level output by up to 12dB for up to four audio components. Simply connect the stereo line level outputs (using stereo RCA-type connectors) to the stereo inputs on the LGB-4. Connect the four stereo outputs on the LGB-4 to inputs on your amplifier, receiver, or whole-house audio controller. Adjust the level knob for each device until all four outputs are at the same volume level. Can be rack-mounted with included dog-ears.