A method of synthesizing a first (L) and a second (R) output signal from an input signal (x). The method comprises: filtering (201) the input signal to generate a filtered signal (Hx); obtaining a correlation parameter (ρ) indicative of a desired correlation between the first and second output signals; obtaining a level parameter (c) indicative of a desired level difference between the first and second input signals; and transforming the input signal and the filtered signal by a matrixing operation (203) into the first and second output signals, where the matrixing operation depends on the correlation parameter and the level parameter.