Hi.
In the video 106 of the Mastering Logic 8, Martin states that you should dither your bounce even if you are bouncing from 32-bit floating point to 24-bit fixed.
This is not correct. You should only use dithering when converting from 32, 24 or 20-bit to 16-bit for CD-mastering, and this should really be the last thing you do to your audio file. No more processing should be made after dither or you will ruin your audio material.
So please don't use dither when going to 24-bit!
More info:
http://www.mil-media.com/pow-r.html
http://www.digido.com/bob-katz/dither-2.html
http://www.pcrecording.com/dither.htm
PS. You are doing a great job with those tutorials and I specially want to thank M. Sitter and S. Horelick for their tutorials that are very informative and easy to grasp, best of all to a reasonable price. THANX!