The BrownBox is a voltage optimizer that was designed to offer a safe range of voltage reduction levels made specifically for the same, era-correct voltages that vintage tube amps were designed around. It lowers the line voltage from your wall to what the designers intended. The change in sound goes from slight to significant, depending on what you are using. An important side effect of the lower or browned out voltage is longer life for tubes, caps and all internal components. The BrownBox cleverly meters the line voltage from the wall, and then can be selectively lowered to the desired amount.