I agree Eivind, and as ever, I've been somewhat lost in translation here. The only time I would recommend obtaining a WAV file of something, is to improve it from it's original state. ie: Sound placed onto a Super 8mm film from a DVD source etc.
Personally, I'd never recommend obtaining a track from a Super 8mm film, simply because, once transferred, it will fall way short of the standards expected from today.
Don't forget here, the tracks I take from a DVD start out life at 25fps, but then need converting to 24fps to get them somewhere near to sync speed to begin with.
In order to be able to achieve this, I try and obtain the best 2ch sound I can from the disc either using converted WAV files or 320kbs files dependant on length of the film involved.