I updated to v.2008 build .30 last Tuesday and all the files I converted since then have been loud & distorted. 

I think automatically punching up the volume like that probably works great for converting full length DVD movies is great, but if you're converting something like a music video, which is already very loud, that extra volume just distorts the sound of the output file.

Is there anyway manually to turn this feature off or adjust it ( to say: Volume +0 DB or 2 DB or -6 DB )?

If not, maybe an new feature idea for the next go around?  Manually adjustable output volume control.