The invention relates to an audio signal processing stage (600) for processing an input audio signal (101) into an output audio signal (103). The audio signal processing stage (600) comprises: a filter bank (105a) defining two or more frequency bands, the filter bank separating the input audio signal (101) into two or more input audio signal components (X(k,b)); a set of two or more band branches(105e) which provide two or more output audio signal components (Y(k,b)). The set of two or more band branches (105e) comprises one or more compressor branches, each comprising a compressor (105b) which compresses the respective input audio signal component (X(k,b)) to provide the respective output audio signal component (Y(k,b)); an inverse filter bank (105d) which generates a summed audio signal(y(t)) by summing the two or more output audio signal components (Y(k,b)); a residual audio signal generating unit (613) which generates a residual audio signal (v(t)) which is a difference between the input audio signal (101) and the summed audio signal(y(t)); a virtual bass unit (107) which generates a virtual bass signal (w(t)) that comprises one or more harmonics of the residual audio signal(v(t)); and a summation unit (109) which generates the output audio signal (103) by summing the summed audio signal (y(t)) and the virtual bass signal (w(t)). A variant (700) of the audio signal processing stage (600), and corresponding audio signal processing methods are also described.