Be patient - we're getting there - one step at a time, but we're getting there.
You finally gave me some usable info - the stereo hookup (plugs for left and right speakers) - is an analog hook up... you can't run a digital signal through them and expect to hear it. This is why I was asking you what your audio was hooked up to. Whatever it is, it will have to have a digital input (and this will apply to your other DVDs too).
A two pronged left/right cord won't work... digital is 1 plug, 1 cable.
Now, if you put a store-bought in any of your players, and hear the audio, that's because there is a PCM track on the DVD, and your player is twigging to the way it's audio is hooked up, and is playing the PCM track automatically.
When you use DVDFab, and do the copy with Dolby, that's the only audio track that gets written, and your DVD(s) have no PCM track to use so you can hear something.
Solution - alter your DVD hook-ups so digital can be played (again, whatever you run the audio through will have to be able to handle a digital signal) OR make sure when you duplicate a disc, you copy only the PCM track, as that is all you are setup to reproduce currently.
If you run across a store-bought with no PCM track option when you start copying, you may have to put that one on hold. Not all discs have it (although it's supposed to be there for compliancy). A change in your equipment to all-digital will cure that problem (or another method, which will involve mucho time at the computer to convert a digital to an analog signal, which you may not want to attempt) are your options.
I hope you're still with me on this...