Digital to Analog conversion

Maybe you should back up a step and tell us:

  1. What servos you are using (links to specs or something is useful).
  2. How many of these servos you plan to control.
  3. What your application for these servos are.

Without this information, we really can't recommend a "best course of action"; the solution you are attempting may be the solution needed, or you might be solving a problem that doesn't really exist. Answering the items above will help us help you.