A Class-G amplifier including a first and second driving transistor configured to receive an input voltage; a first supplying terminal connected to the first driving transistor to supply a first supplying voltage. The amplifier also comprises: a second supplying terminal connected to the second driving transistor to supply a second supplying voltage in absolute value higher than said first voltage; a first power transistor connected to the first driving transistor to form a first Sziklai pair structured to be activated by a first input voltage lower in absolute value than the first supplying voltage; a second power transistor connected to the second driving transistor to form a second Sziklai pair structured to be activated by an input signal comprised between the first supplying voltage and the second supplying voltage.