A specification for power amplifiers which suggests the degree of control that the amplifier exercises over a connected loudspeaker. It is the ratio of the nominal impedance of the speaker (and is typically quoted for eight ohms) to the internal impedance of the output stage of the amplifier. A high internal impedance for the amplifier means that its frequency response will vary with real-world speakers since their impedance varies across their frequency range. It also means that the driver, which wants to do its own thing under the influence of air, its suspension and so forth, rather than what the signal is telling it to do, will face a relatively high impedance to the voltage it is generating back into the amplifier. Consequently it will be freer to do its own thing, rather than what the amplifier is telling it to do. However the damping factor quoted for amplifiers does not take into account the impedance of the wiring between amplifier and loudspeakers, nor the impedance of the speakers' own voice coils. Consequently there is only a modest performance gain between a damping factor of, say, 60 and one of 600.