In Reaper, the Lame Codec used to create MP3 does not need to be dithered... I can totally create mp3's from 32 bit waveforms no problem..
However!!
Many of the digital distributors, ( I've recently started distributing my tunes to the download stores, ) and many of the distributors want 16 bit wav files.
So.. What's a guy to do? Dither. And know what it is.
My favorite type of dither is Pow r1. Because, I need a favorite type of dither, and thats it. I'm also into triangular, and I quite like Pow r3 as well.
Unfortunately, I hear no difference.. But maybe I would in a completely tuned, perfectly silent, absolutely sound proofed mastering studio.
That's that.. Choose 1 and go with it.
Dither is supposed to be applied after the mastering stage, when converting a high bit wav to a 16 bit wave. If you are using dither throughout your projects, on various audio parts, that is screwing you up, "big time!"