Quote Originally Posted by Sir Terrence the Terrible
Correct. I would not use a A/D converter that had fixed dither.
The larger question is do you have a choice in the matter? Here's a random link from the web for you. And here's an excerpt for your education.

All A/D converters have built-in dither. It is a property of the converter chip, manifesting itself as an unavoidable noise floor. A/D converter chip manufacturer's use this noise - on purpose - to linearise the chip's behavior at lower signal levels.