What the heck is dithering all about? Should I care? The Sonar Help feature isn't doing me any good. Should I select none, rectangular, etc? I use Sonar exclusively for midi, but I'm doing full orchestra with several synths going (Play, Aria and Vienna).
AMD dual core, 3 GHz; 8 GB Ram
500 GB WD Blue, external 500 GB Glyph
EWSO Gold, GPO, Vienna Sp. Ed. 1
M-Audio 2496 sound card

When you export the project to audio from a higher bit rate to, say, 16 bits for CD, you need to use dithering to "fill in the bit-gaps". I use Powr-3 IIRC.

Dithering is a way of pushing down the noise floor a couple more dB. It is more of a best practice than audible at today's bit depths.

I see. It doesn't affect what you do when you are working, just when you export. I've been using power 2, is there any benefit to going to power 3?

The different dithers have more volume in different frequencies. They all add roughly the same amount of noise but different dithers are shaped differently and therefore harder to hear and appear quieter.

I export files at 24 bit making the dither pretty irrelevant. At sixteen bit, there could be moments where the dither is audible.

You can see the shapes of the dithers if you export silence to a Wave file using the dither, then re-import the wav and normalize it. Then, play it and turn it up so you can hear the noise. You can also but a Freq Analyst on it so you can see where the noise is more and where it is less for the particular algorithm.
 
This one is Power 3.
 

When the dither is audible, what does it sound like?

White Noise

Think of it as the New Dolby Noise reduction for digital music.  The more I read up on it, the more I decided it was only important for people who are working in a much higher realm of quality than a hack like me. 
I have therefore stayed in 44.1 for recording and add a little power 3 to my exports. Sonar process in 32 bit so we kinda have to export with dither, but I bet if you compared a dithered and a none dithered song no body will hear a difference. 

I suspected as much. So maybe I'll just choose "none." Why use CPU needlessly? thanks for that, Cactus.