An apparatus for encoding an audio input signal to obtain an encoded audio signal, wherein the apparatus comprises: a transformation module configured to transform the audio input signal, being represented in an original domain, from the original domain to a transform domain to obtain a transformed audio signal, being represented in the transform domain, and an encoding module, configured to quantize the transformed audio signal to obtain a quantized signal, and configured to encode the quantized signal to obtain the encoded audio signal, characterized in that the transformation module is configured to transform the audio input signal using a plurality of predefined power values of quantization noise in the original domain and using a plurality of predefined power values of the quantization noise in the transform domain for conducting transformation, wherein the original domain is a spectral domain, wherein the transformation module is configured to transform the audio input signal using a transformation matrix A, wherein the transformation module is configured to transform the audio input signal according to: d = A x, wherein d indicates the transformed audio signal, wherein x indicates the audio input signal, wherein A indicates the transformation matrix depending on the plurality of predefined power values of the quantization noise in the original domain and depending on the plurality of predefined power values of the quantization noise in the transform domain, wherein A = p − 1 − p 2 + 1 − p 2 p, wherein p = ± d 0 − c 1 c 0 − c 1, wherein C ex = d 0 ⋅ ⋅ d 1, wherein C ed = c 0 0 0 c 1, wherein C ex is a first covariance matrix comprising on its diagonal the plurality of predefined power values of the quantization noise in the original domain, wherein do and d 1 are matrix coefficients of C ex; and wherein C ed is a second covariance matrix comprising on its diagonal the plurality of predefined power values of the quantization noise in the transform domain, wherein c 0 and c 1 are matrix coefficients of C ed. a transformation module configured to transform the audio input signal, being represented in an original domain, from the original domain to a transform domain to obtain a transformed audio signal, being represented in the transform domain, and an encoding module, configured to quantize the transformed audio signal to obtain a quantized signal, and configured to encode the quantized signal to obtain the encoded audio signal, characterized in that the transformation module is configured to transform the audio input signal using a plurality of predefined power values of quantization noise in the original domain and using a plurality of predefined power values of the quantization noise in the transform domain for conducting transformation, wherein the original domain is a spectral domain, wherein the transformation module is configured to transform the audio input signal using a transformation matrix A, wherein the transformation module is configured to transform the audio input signal according to: d = A x, wherein d indicates the transformed audio signal, wherein x indicates the audio input signal, wherein A indicates the transformation matrix depending on the plurality of predefined power values of the quantization noise in the original domain and depending on the plurality of predefined power values of the quantization noise in the transform domain, wherein A = p − 1 − p 2 + 1 − p 2 p, wherein p = ± d 0 − c 1 c 0 − c 1, wherein C ex = d 0 ⋅ ⋅ d 1, wherein C ed = c 0 0 0 c 1, wherein C ex is a first covariance matrix comprising on its diagonal the plurality of predefined power values of the quantization noise in the original domain, wherein do and d 1 are matrix coefficients of C ex; and wherein C ed is a second covariance matrix comprising on its diagonal the plurality of predefined power values of the quantization noise in the transform domain, wherein c 0 and c 1 are matrix coefficients of C ed.