Preamplifier system to adjust the level of an audio signal, said system comprising a transient adjustment line formed by a conventional symmetric amplifier with digitally adjustable gain and a steady adjustment line formed by a coil with multiple selectable windings, each receiving the input of the preamplifier system, each adjustment line having an input and an output, said system further comprising a setting device to produce a setting adjustment value of the audio signal, a controller to receive the setting adjustment value and to control the transient adjustment line and the steady adjustment line, a switching module connected to an output of the preamplifier system and to the output of the transient adjustment line and to the output of the steady adjustment line, the controller being configured to: - detect a change of the setting value of the audio signal, and in this case to successively perform the steps of: - control the switching module to select as the output of the preamplifier system, the transient adjustment line output, - adjust the level of the audio signal through the transient adjustment line according to the new setting value, - detect an absence of change of the setting value of the audio signal, and in this case to successively perform the steps of: - adjust the level of the audio signal through the steady adjustment line according to the new setting value, - control the switching module to connect the output of the steady adjustment line and the output of the transient adjustment line with the output of the preamplifier system, - control the switching module to connect the output of the preamplifier system only with the steady adjustment line output. - detect a change of the setting value of the audio signal, and in this case to successively perform the steps of: - control the switching module to select as the output of the preamplifier system, the transient adjustment line output, - adjust the level of the audio signal through the transient adjustment line according to the new setting value, - control the switching module to select as the output of the preamplifier system, the transient adjustment line output, - adjust the level of the audio signal through the transient adjustment line according to the new setting value, - detect an absence of change of the setting value of the audio signal, and in this case to successively perform the steps of: - adjust the level of the audio signal through the steady adjustment line according to the new setting value, - control the switching module to connect the output of the steady adjustment line and the output of the transient adjustment line with the output of the preamplifier system, - control the switching module to connect the output of the preamplifier system only with the steady adjustment line output. - adjust the level of the audio signal through the steady adjustment line according to the new setting value, - control the switching module to connect the output of the steady adjustment line and the output of the transient adjustment line with the output of the preamplifier system, - control the switching module to connect the output of the preamplifier system only with the steady adjustment line output.