Wolfson's Class-G amplifiers switch the supply rail voltage to the amplifier by using a dual-mode charge-pump with variable frequency. This decreases power consumption and increases efficiency.
Wolfson's Class-W technology takes this a stage further, and is used in their CODECs, where a digital signal path is present. It includes control logic with predictive signal processing and adaptive dual-mode charge pump. This further reduces power consumption. It also improves audio quality because signal peaks are not clipped and does not introduce extra delays.