That's a really good one. Very accurate (which is quite rare).
An important point about all this is that the topic has been horribly raped by marketing. Dithering is important to keep in mind when truncating an audio signal, but which one you use (i.e. which kind of shaping and other voodoo) is TOTALLY overrated.
The main reason for this is that nearly all real world signals already contain WAY MORE noise than a dither would add. This makes the dither obsolete.
The second reason is that we're talking about events happening at the very last end of human perception and several dBs below the typical noise of 99.9% of the analogue gear out there (which is roughly around -70dB SNR, but 16bit dithering has a level around -90dB ) - in this case, we're neither able to measure any kind of effect nor will most people on most playback systems hear the effects of dithering at all.
There's way too much esoteric hype around dithering IMO. Fact is, most listeners won't care at all. Don't waste too much time with it. Dithering gets really important in low precision applications (below 16 bit), but is nearly useless at higher precisions (again, because we're working with signal that already contains noise far above the least significant bit).
BTW, one of the best introduction I've heard is:
…one of the earliest [applications] of dither came in World War II. Airplane bombers used mechanical computers to perform navigation and bomb trajectory calculations. Curiously, these computers (boxes filled with hundreds of gears and cogs) performed more accurately when flying on board the aircraft, and less well on ground. Engineers realized that the vibration from the aircraft reduced the error from sticky moving parts. Instead of moving in short jerks, they moved more continuously. Small vibrating motors were built into the computers, and their vibration was called dither from the Middle English verb "didderen," meaning "to tremble." Today, when you tap a mechanical meter to increase its accuracy, you are applying dither, and modern dictionaries define dither as a highly nervous, confused, or agitated state. In minute quantities, dither successfully makes a digitization system a little more analog in the good sense of the word.
—Ken Pohlmann,
Principles of Digital Audio[1]