The PS 4x4 features a backlit linear meter to monitor input voltage, which gives the user a familiar analog style readout when monitoring voltage from a power source. The PS 4x4 has a backlit linear Ammeter showing Load Current in amperes. This additional meter gives an analog "real-world" look at how much power you are using ...hence the term "power station". While the associated voltmeter stays relatively stable and varies slightly with line voltage and house wiring, the ammeter varies much more, as power is consumed. For example, if the unit is in a rack with digital equipment and preamps, it may not vary a lot (even if you had 8 200 watt network computers hooked up, it would show if all are up and running). However, if it is in a rack with one or more power amps, the meter's indicator may be bouncing all around - and providing a great indication of output.