i would convert to the highest quality avi i could. vobs are just a container for mpeg files http://en.wikipedia.org/wiki/VOB so determining the encoding of the original files in the vob and then reading that format without recompression would be best. "sometimes you can just rename them .mpeg files" http://forums.adobe.com/thread/464549
what software does your director use? you can export as avi from final cut pro and quicktime for sure.  

Yes, I am affraid of too much compressiom degrading the audio quality for sure.

Thank you very much Swamptooth. I think he uses Final Cut, but I am not sure. I will ask him. Since I know nothing of Mac I can`t help him very much.

Thx

Just to give more information for other users.

I am using a freeware convertions tool called FormatFactory to convert my files to .AVI and than I can import it into Sonar X1.

Thank you to you all for the kind help.

Best Regards