An amplifier drives you Loudspeakers. The Loudspeakers is the load for the amplifier. Load stability means that the amplifier has a stable performance up to its rated power, across all frequencies Performance at Loudspeakers can deliver. It should be noted that it is undemanding and critical to operate Loudspeakers there, with all facets in between.
when is a Loudspeakers a critical one Loudspeakers? At least whenever there are large fluctuations in the impedance over frequency and when a minimum below e.g. B. 4 Ohm is, e.g. B. at 2 ohms. If this minimum is in the bass range and the amplifier is not load stable, then there are several possibilities: one of them would be that the bass simply does not get louder, even if you turn it up.
A pair of Loudspeakers is a complicated structure made up of electrical and mechanical components. Electrical components in the switch and in the windings of the individual Chassis, which turn into one air gap of a magnet move and the the Membran move, there are mechanical resistances such as air resistance or the Resistance due to the mechanical suspension and frequency-dependent resistance due to the shape of the loudspeaker housing. As a result, a lot depends on the frequency.
Through the movement of Kitchen sink of a chassis in the air gap, a voltage is "sent back" to the amplifier, which has to cope with it. The Loudspeakers is not a simple linear system like an ohmic resistor of 4 ohms. There are electronic resistors that can be used to simulate a measurement in order to get a rough estimate of the load stability, but they are commercially available Loudspeakers still more complicated than these electronic resistors and most publications in HiFi-Magazines in this regard should be treated with caution.