OK I think I finally got this work:

Step 1 acidrip dvd tracks to avi (audio --> mp3). acidrip seems to be the only sw capable of reading the dvd on ubuntu, even with libdvdcss on board I can't even open it in a file manager.

Step 2 open avi in avidemux and copy-save audio to .mp3. It's a bit lo-res but doesn't have the crackling/skipping, so suitable for the tablet at least. Bonus: I can still watch the video, if I so choose (unlikely).

I just want to add: FUCKING JESUS MOTHERFUCK THAT WAS HARD.

Definitely must be an easier way. Did you try Handbrake or MakeMKV?

Yeah, it should be easier. After >6-hours in, I'm taking whatever works.  :-O~~~

Handbrake isn't in the Ubuntu repos (guess I could add it), so I moved on to acidrip, which someone reckoned is the best thing anyway.

Weird thing is if I copy/save the raw audio from a copied 1G vob out of avidemux (it won't directly read the dvd, like everything else except acidrip), it comes with crackling/skipping on board (there are two tracks on the vob: an ac3 in 5.1, and a stereo pcm). acidrip doesn't even let you pick which track to use, apparently it guessed right.