A driver system for a differential piezoelectric actuator system, the driver system comprising: an inductor; a driver circuit (11, 12) comprising driver switches (S1-S6) for selectively facilitating transfer of energy between first and second actuators (PZT1, PZT2) of the differential piezoelectric actuator system and the inductor and between a voltage supply node (Vbatt) and the inductor; and control circuitry configured to: determine whether a next phase in which to operate the driver circuit is a first charging phase or a first recovery phase; in the first charging phase: in a first sub-phase of the first charging phase, operate the driver switches (S1-S6) to transfer energy from the first actuator to the inductor; in a second sub-phase of the first charging phase, operate the driver switches (S1-S6) to transfer energy from the voltage supply node (Vbatt) to the inductor; and in a third sub-phase of the first charging phase, operate the driver switches (S1-S6) to transfer energy from the inductor to the second actuator; and in the first recovery phase: in a first sub-phase of the first recovery phase, operate the driver switches (S1-S6) to transfer energy from the first actuator to the inductor; in a second sub-phase of the first recovery phase, operate the driver switches (S1-S6) to transfer energy from the inductor to the second actuator; and in a third sub-phase of the first recovery phase, operate the driver switches (S1-S3) to transfer energy from the inductor to the voltage supply node (Vbatt). an inductor; a driver circuit (11, 12) comprising driver switches (S1-S6) for selectively facilitating transfer of energy between first and second actuators (PZT1, PZT2) of the differential piezoelectric actuator system and the inductor and between a voltage supply node (Vbatt) and the inductor; and control circuitry configured to: determine whether a next phase in which to operate the driver circuit is a first charging phase or a first recovery phase; in the first charging phase: in a first sub-phase of the first charging phase, operate the driver switches (S1-S6) to transfer energy from the first actuator to the inductor; in a second sub-phase of the first charging phase, operate the driver switches (S1-S6) to transfer energy from the voltage supply node (Vbatt) to the inductor; and in a third sub-phase of the first charging phase, operate the driver switches (S1-S6) to transfer energy from the inductor to the second actuator; and in the first recovery phase: in a first sub-phase of the first recovery phase, operate the driver switches (S1-S6) to transfer energy from the first actuator to the inductor; in a second sub-phase of the first recovery phase, operate the driver switches (S1-S6) to transfer energy from the inductor to the second actuator; and in a third sub-phase of the first recovery phase, operate the driver switches (S1-S3) to transfer energy from the inductor to the voltage supply node (Vbatt). determine whether a next phase in which to operate the driver circuit is a first charging phase or a first recovery phase; in the first charging phase: in a first sub-phase of the first charging phase, operate the driver switches (S1-S6) to transfer energy from the first actuator to the inductor; in a second sub-phase of the first charging phase, operate the driver switches (S1-S6) to transfer energy from the voltage supply node (Vbatt) to the inductor; and in a third sub-phase of the first charging phase, operate the driver switches (S1-S6) to transfer energy from the inductor to the second actuator; and in a first sub-phase of the first charging phase, operate the driver switches (S1-S6) to transfer energy from the first actuator to the inductor; in a second sub-phase of the first charging phase, operate the driver switches (S1-S6) to transfer energy from the voltage supply node (Vbatt) to the inductor; and in a third sub-phase of the first charging phase, operate the driver switches (S1-S6) to transfer energy from the inductor to the second actuator; and in the first recovery phase: in a first sub-phase of the first recovery phase, operate the driver switches (S1-S6) to transfer energy from the first actuator to the inductor; in a second sub-phase of the first recovery phase, operate the driver switches (S1-S6) to transfer energy from the inductor to the second actuator; and in a third sub-phase of the first recovery phase, operate the driver switches (S1-S3) to transfer energy from the inductor to the voltage supply node (Vbatt). in a first sub-phase of the first recovery phase, operate the driver switches (S1-S6) to transfer energy from the first actuator to the inductor; in a second sub-phase of the first recovery phase, operate the driver switches (S1-S6) to transfer energy from the inductor to the second actuator; and in a third sub-phase of the first recovery phase, operate the driver switches (S1-S3) to transfer energy from the inductor to the voltage supply node (Vbatt).