I don't think it's like Dolby. Dolby boosted the very high end of the sound above the noise level on the tape and then when you play it back with Dolby On you suppress the same freq range aligning the original signal and suppressing the high end tape noise.
The problem with this was that if you played it back with Dolby off (or the wrong dolby) you could just get extra tape hiss.
THIS IS NOT THE CASE WITH DITHER.
When you Dither appropriately, you get better sound on all playback environments no matter the settings on the device doing the playback. Dither suppresses the noise floor by randomizing it and spreading it over a greater frequency band (like the audible range). DITHER WILL MAKE YOUR RECORDINGS BETTER.
Use Dither when changing Bit Depth (like 32 to 24 or 24 to 16). Don't use Dither when going from 88.2 Samples per Sec to 44.1. I have sources that say going from 48 to 44.1 use dither and others that say don't.
http://www.amazon.com/Digital-Audio-Explained-For-Engineer/dp/141960001X/ref=sr_1_2?ie=UTF8&qid=1383132288&sr=8-2&keywords=sweetwater+digital+recording This book says it is appropriate to use dither when changing sample rates where the sample rate is NOT an even division... like 48 to 44.1 but not 88.2 to 44.1.
Basically, since it adds the slightest bit of white noise, you want to avoid it where it is not necessary. So, for this reason, I add Dither when going from 32 bit mixdown's to export to 24 bit waves. I usually change sample rate and bit depth at the same time.