How your 24bit audio was made? If your audio card gives out 24-bit, then you may loose bits because there are no true 24-bit converters. At top you could use a smooth hard-limiter (which processes each sample separately). It takes out random high peaks and makes the audio more analogue. At bottom the dither noise may not be necessary if the audio source's noise floor is high enough. All dither tests seems to test against the mathematical sine wave which you don't get if you do acoustic music. Noiseshaping dither is suspectible as well because one may then wonder where the high frequency noise introduced by the dither goes to. No amplifier near me have a dither noise remover. Juhana -- http://music.columbia.edu/mailman/listinfo/linux-graphics-dev for developers of open source graphics software