Just for the record...
The video on Laserdisc is analogue composite video.
The audio can be analogue or Digital in either DTS 5.1 , PCM stereo or Dolby Digital 5.1, all of which can be ripped bit for bit as it is a true digital signal.
The audio often sounds better on laserdisc in 5.1 than on DVD on 5.1 because the 5.1 mixes for laserdisc were 'pure' 5.1 mixes.
That is they were designed to be played back through 5.1 equipment *only* and the mix was done accordingly, and was usually very close to the cinematic release. If you were dumb enough to play the Laserdisc 5.1 mix on stereo equipment (somehow) it may well sound like crap but that was to be expected.
For DVD being a 'mainstream consumer format' often the 5.1 mix is totally different to the laserdisc because studios were worried that people would select the 5.1 mix even if they had only stereo or mono through the TV speaker, and often a 5.1 mix when downmixed like that becomes muddled and the dialogue can be hard to hear etc.
So they decided to redo the 5.1 mix for a lot of DVD titles so that it would still sound OK if played back in Stereo or mono. This of course makes the 5.1 mix somewhat "crappier" (technical term).
So the DVD mix can sound thin and flat compared to the laserdisc version of the same movie if they have dumbed down the 5.1 for DVD, but on titles where they used the same mix as for the laserdisc, it sounds identical on both formats.
So you can take the DTS or DD track from laserdisc and mux it onto the DVD to get audio goodness that may otherwise have been lacking.