An audio system comprising a controller, an audio processor and an amplifier, the controller configured to: receive an amplifier-operating-condition-signal representative of an operating condition of the amplifier; receive a maximum-threshold-value; and generate control signalling based on the amplifier-operating-condition-signal and the maximum-threshold-value, wherein the control signalling is configured to set an operating parameter of the audio processor; and wherein the audio system further comprises a load, and wherein the controller is further configured to: determine or receive a frequency-dependent impedance function of the load; and wherein generating the control signalling is also based on the frequency-dependent impedance function of the load; and wherein the frequency-dependent impedance function of the load defines one or more low-impedance-frequency-bands (324, 326) and one or more high-impedance-frequency-bands (328, 330), and wherein the control signalling is configured to configure the audio processor to attenuate audio signals in a low-impedance-frequency-band to a greater extent than audio signals in a high-impedance-frequency-band, wherein the one or more low-impedance frequency bands are frequency bands for which all impedance values are less than a low-impedance-frequency-threshold, the one or more high-impedance-frequency-bands are frequency bands for which all impedance values are greater than a high-impedance-frequency-threshold and wherein the low-impedance-frequency-threshold is equal to or less than the high-impedance-frequency-threshold. receive an amplifier-operating-condition-signal representative of an operating condition of the amplifier; receive a maximum-threshold-value; and generate control signalling based on the amplifier-operating-condition-signal and the maximum-threshold-value, wherein the control signalling is configured to set an operating parameter of the audio processor; and wherein the audio system further comprises a load, and wherein the controller is further configured to: determine or receive a frequency-dependent impedance function of the load; and wherein generating the control signalling is also based on the frequency-dependent impedance function of the load; and wherein the frequency-dependent impedance function of the load defines one or more low-impedance-frequency-bands (324, 326) and one or more high-impedance-frequency-bands (328, 330), and wherein the control signalling is configured to configure the audio processor to attenuate audio signals in a low-impedance-frequency-band to a greater extent than audio signals in a high-impedance-frequency-band, wherein the one or more low-impedance frequency bands are frequency bands for which all impedance values are less than a low-impedance-frequency-threshold, the one or more high-impedance-frequency-bands are frequency bands for which all impedance values are greater than a high-impedance-frequency-threshold and wherein the low-impedance-frequency-threshold is equal to or less than the high-impedance-frequency-threshold. determine or receive a frequency-dependent impedance function of the load; and wherein generating the control signalling is also based on the frequency-dependent impedance function of the load; and wherein the frequency-dependent impedance function of the load defines one or more low-impedance-frequency-bands (324, 326) and one or more high-impedance-frequency-bands (328, 330), and wherein the control signalling is configured to configure the audio processor to attenuate audio signals in a low-impedance-frequency-band to a greater extent than audio signals in a high-impedance-frequency-band, wherein the one or more low-impedance frequency bands are frequency bands for which all impedance values are less than a low-impedance-frequency-threshold, the one or more high-impedance-frequency-bands are frequency bands for which all impedance values are greater than a high-impedance-frequency-threshold and wherein the low-impedance-frequency-threshold is equal to or less than the high-impedance-frequency-threshold.