A drive system comprises a splitter (107) which generates a low frequency signal and high frequency signal from an input signal. A first drive circuit (111, 115) is coupled to the splitter (107) and generates a drive signal for an audio driver (105) from the low frequency signal. A second drive circuit (117, 119) is coupled to the splitter (117) and generates a drive signal for a second audio driver (101) from the high frequency signal. The second drive circuit (117, 119) provides a bass frequency extension for the second audio driver (101) by applying low frequency boost to the low frequency signal. A processor (125) determines a driver excursion indication for the second audio driver (101) and a controller (127) performs a combined adjustment of a cross-over frequency for the high and low frequency signals and a characteristic of the low frequency boost based on the driver excursion indication. The invention may provide improved interworking between e.g. a subwoofer and satellite speakers.