Hello,
I used mplayer to create a PCM file from a dvd with a command like this

I'm not sure (please correct me if I'm wrong), but I think could be some loss during the decoding process, so my question is:
Is there any better way to get a wav from a .vob?
Thanks in advance.

you could use http://neuron2.net/dgmpgdec/dgmpgdec.html to demux any audio from a series of vobs, and then another app (depending on the type of audio) for decoding (if you are on windows that is).