An audio processing system (100 in fig. 1) configured to accept an audio bitstream, the audio processing system comprising: a front-end component, which includes: - a dequantization stage adapted to receive quantized spectral coefficients and to output a first frequency-domain representation of an intermediate signal; and - an inverse transform stage for receiving the first frequency-domain representation of the intermediate signal and synthesizing, based thereon, a time-domain representation of the intermediate signal; a processing stage, which includes: - an analysis filterbank for receiving the time-domain representation of the intermediate signal and outputting a second frequency-domain representation of the intermediate signal; - at least one processing component (105, 106, 107) for receiving said second frequency-domain representation of the intermediate signal and outputting a frequency-domain representation of a processed audio signal; and - a synthesis filterbank for receiving the frequency-domain representation of the processed audio signal and outputting a time-domain representation of the processed audio signal; and - a sample rate converter for receiving said time-domain representation of the processed audio signal and outputting a reconstructed audio signal sampled at a target sampling frequency, wherein the respective internal sampling rates of the time-domain representation of the intermediate audio signal and of the time-domain representation of the processed audio signal are equal, and wherein said at least one processing component includes: - a parametric upmix stage for receiving a downmix signal with M channels and outputting, based thereon, a signal with N channels, wherein the parametric upmix stage is operable at least in a mode where 1 ≤ M < N and a mode where 1 ≤ M = N; characterised in that said at least one processing component further includes: - a first delay stage configured to compensate the current mode of the parametric upmix stage in order for the processing stage to have a constant total delay. a front-end component, which includes: - a dequantization stage adapted to receive quantized spectral coefficients and to output a first frequency-domain representation of an intermediate signal; and - an inverse transform stage for receiving the first frequency-domain representation of the intermediate signal and synthesizing, based thereon, a time-domain representation of the intermediate signal; - a dequantization stage adapted to receive quantized spectral coefficients and to output a first frequency-domain representation of an intermediate signal; and - an inverse transform stage for receiving the first frequency-domain representation of the intermediate signal and synthesizing, based thereon, a time-domain representation of the intermediate signal; a processing stage, which includes: - an analysis filterbank for receiving the time-domain representation of the intermediate signal and outputting a second frequency-domain representation of the intermediate signal; - at least one processing component (105, 106, 107) for receiving said second frequency-domain representation of the intermediate signal and outputting a frequency-domain representation of a processed audio signal; and - a synthesis filterbank for receiving the frequency-domain representation of the processed audio signal and outputting a time-domain representation of the processed audio signal; and - a sample rate converter for receiving said time-domain representation of the processed audio signal and outputting a reconstructed audio signal sampled at a target sampling frequency, wherein the respective internal sampling rates of the time-domain representation of the intermediate audio signal and of the time-domain representation of the processed audio signal are equal, and wherein said at least one processing component includes: - a parametric upmix stage for receiving a downmix signal with M channels and outputting, based thereon, a signal with N channels, wherein the parametric upmix stage is operable at least in a mode where 1 ≤ M < N and a mode where 1 ≤ M = N; characterised in that said at least one processing component further includes: - a first delay stage configured to compensate the current mode of the parametric upmix stage in order for the processing stage to have a constant total delay. - an analysis filterbank for receiving the time-domain representation of the intermediate signal and outputting a second frequency-domain representation of the intermediate signal; - at least one processing component (105, 106, 107) for receiving said second frequency-domain representation of the intermediate signal and outputting a frequency-domain representation of a processed audio signal; and - a synthesis filterbank for receiving the frequency-domain representation of the processed audio signal and outputting a time-domain representation of the processed audio signal; and - a sample rate converter for receiving said time-domain representation of the processed audio signal and outputting a reconstructed audio signal sampled at a target sampling frequency, - a parametric upmix stage for receiving a downmix signal with M channels and outputting, based thereon, a signal with N channels, wherein the parametric upmix stage is operable at least in a mode where 1 ≤ M < N and a mode where 1 ≤ M = N; - a first delay stage configured to compensate the current mode of the parametric upmix stage in order for the processing stage to have a constant total delay.