All of your low pass filters won't affect 50 Hz, they pass 50 Hz. That is their job.
You seem to be missing the point that the low pass filters pass the frequencies below the frequency of the low pass filter.
Try playing a 200 Hz signal with the 80 Hz low pass filter on, then off, and tell us what you hear.
You seem to be missing the point that the low pass filters pass the frequencies below the frequency of the low pass filter.
Try playing a 200 Hz signal with the 80 Hz low pass filter on, then off, and tell us what you hear.