This works only if thge noise is in the high frequency part of the spectrum and the signal is in the low frequency part of the spectrum. That is, both spectra do not overlap.
If the signal has high frequency components, those will be attenuated, too.
It depends very much on the properties of the signal and the noise, whether you can treat them differently.
Dynamic Noise Limiting (DNL) in tape decks, for example, works by attenuating the high frequency components of the signal depending on the amplitude of the signal. This reduces high frequency noise in quiet passages of the music, but not in loud passages. This works because the tape noise is mainly in the high frequency part of the audio spectrum whereas the signal (music) is mainly in the middle frequency range.
But I think the question of deflow was not so much about how to filter noise but what effects the feedback loop in an ampplifier has on noise.