A boost control signal generator (400, 500,600) for controlling a DC-DC-booster, the boost control signal generator comprising: a boost control input (402, 502,608) configured to receive an audio signal comprising a plurality of audio sample values; a delay line (440, 540, 620) having a delay line input coupled to the boost control input (402, 502,608) and a delay line output (426, 526,616) wherein the delay line is configured to output a maximum delayed value of the delayed audio sample values; a maximum value detector (412, 512,618) having a first input coupled to the boost control input (402, 502,608), a second input coupled to the delay line output (426,526,616) and an output coupled to a boost control output (414, 514, 618), wherein the maximum value detector is configured to determine the maximum of the current audio sample value and the maximum delayed value as a boost control signal value to be output on the boost control output (414, 514, 618); wherein the delay line (440, 540,620) comprises a plurality of delay stages (420,420'; 530,530'; 610a,610b,610k) arranged between the delay line input and the delay line output, each of the delay-stages including a delay-stage-input, a delay-stage-output, a delay-stage-maximum-value-detector (424,424';524,524';602a,602b,602k) coupled to the respective delay-stage-output, and at least one delay element (416,416';516,516';604a,604b,604k); and wherein each delay-stage-maximum-value-detector (424,424';524,524';602a,602b,602k) has at least one input coupled to the at least one delay element output and an input coupled to the delay-stage-input, and configured to determine a maximum value of the delayed audio samples in each of the delay stages, and configured to provide the determined maximum value of the delayed audio samples in each of the delay stages to the succeeding delay stage; and wherein the determined maximum-delayed-value is the determined maximum value of the final delay stage of the plurality of delay stages; and wherein in operation the sample rate of each delay stage is less than the sample rate of the preceding delay stage. a boost control input (402, 502,608) configured to receive an audio signal comprising a plurality of audio sample values; a delay line (440, 540, 620) having a delay line input coupled to the boost control input (402, 502,608) and a delay line output (426, 526,616) wherein the delay line is configured to output a maximum delayed value of the delayed audio sample values; a maximum value detector (412, 512,618) having a first input coupled to the boost control input (402, 502,608), a second input coupled to the delay line output (426,526,616) and an output coupled to a boost control output (414, 514, 618), wherein the maximum value detector is configured to determine the maximum of the current audio sample value and the maximum delayed value as a boost control signal value to be output on the boost control output (414, 514, 618); wherein the delay line (440, 540,620) comprises a plurality of delay stages (420,420'; 530,530'; 610a,610b,610k) arranged between the delay line input and the delay line output, each of the delay-stages including a delay-stage-input, a delay-stage-output, a delay-stage-maximum-value-detector (424,424';524,524';602a,602b,602k) coupled to the respective delay-stage-output, and at least one delay element (416,416';516,516';604a,604b,604k); and wherein each delay-stage-maximum-value-detector (424,424';524,524';602a,602b,602k) has at least one input coupled to the at least one delay element output and an input coupled to the delay-stage-input, and configured to determine a maximum value of the delayed audio samples in each of the delay stages, and configured to provide the determined maximum value of the delayed audio samples in each of the delay stages to the succeeding delay stage; and wherein the determined maximum-delayed-value is the determined maximum value of the final delay stage of the plurality of delay stages; and wherein in operation the sample rate of each delay stage is less than the sample rate of the preceding delay stage.