An audio signal processing device for downmixing of a first input signal ( X 1) and a second input signal ( X 2) to a downmix signal ( X̃ D), wherein the first input signal ( X 1) and the second input signal ( X 2) are at least partly correlated, comprising: a dissimilarity extractor configured to receive the first input signal ( X 1) and the second input ( X 2) signal as well as to output an extracted signal ( Û 2), which is lesser correlated with respect to the first input signal ( X 1) than the second input signal ( X 2) and a combiner configured to combine the first input signal ( X 1) and the extracted signal ( Û 2) in order to obtain the downmix signal ( X̃ D), wherein the dissimilarity extractor comprises a similarity estimator configured to provide filter coefficients ( W, | W |) for obtaining signal parts ( WX 1, | WX 1 |) of the first input signal ( X 1) being present in the second input signal ( X 2) from the first input signal ( X 1), wherein the dissimilarity extractor comprises a similarity reducer configured to reduce the obtained signal parts ( WX 1, | WX 1 |) of the first input signal being present in the second input signal ( X 2) based on the filter coefficients ( W, | W |), wherein the similarity reducer comprises a signal suppression stage (10b, 10b') having a signal suppression device configured to multiply the second input signal ( X 2) or a signal ( X ' 2) derived from the second input signal ( X 2) with a suppression gain factor in order to obtain the extracted signal ( Û 2), wherein the suppression gain factor is chosen in such way that a mean squared error between the extracted signal ( Û 2) and a signal part ( U 2) of the second input signal ( X 2), which signal part (U 2) is uncorrelated with the first input signal ( X 1), is minimized. a dissimilarity extractor configured to receive the first input signal ( X 1) and the second input ( X 2) signal as well as to output an extracted signal ( Û 2), which is lesser correlated with respect to the first input signal ( X 1) than the second input signal ( X 2) and a combiner configured to combine the first input signal ( X 1) and the extracted signal ( Û 2) in order to obtain the downmix signal ( X̃ D), wherein the dissimilarity extractor comprises a similarity estimator configured to provide filter coefficients ( W, | W |) for obtaining signal parts ( WX 1, | WX 1 |) of the first input signal ( X 1) being present in the second input signal ( X 2) from the first input signal ( X 1), wherein the dissimilarity extractor comprises a similarity reducer configured to reduce the obtained signal parts ( WX 1, | WX 1 |) of the first input signal being present in the second input signal ( X 2) based on the filter coefficients ( W, | W |), wherein the similarity reducer comprises a signal suppression stage (10b, 10b') having a signal suppression device configured to multiply the second input signal ( X 2) or a signal ( X ' 2) derived from the second input signal ( X 2) with a suppression gain factor in order to obtain the extracted signal ( Û 2), wherein the suppression gain factor is chosen in such way that a mean squared error between the extracted signal ( Û 2) and a signal part ( U 2) of the second input signal ( X 2), which signal part (U 2) is uncorrelated with the first input signal ( X 1), is minimized.