spinefarm: It is a digital mastering... that kills the audio quality if you screw it.
That will kill it also, yes, but I think on that particular album, it's the audio compression as well (compressed so much it distorts). I have not heard it and am only restating what others have told me.
After hearing some of my older MP3 songs as FLAC/Redbook, I never wanted MP3 again. Granted those were old, lower bitrate (192, 160, maybe even 128 *shutter*), so the comparison is VERY unfair. I'd have to give some GOG soundtracks a listen to see what I think.
The best version is always whatever you started with. I made some recordings using the RealAudio format (glad that died). Those recordings will (sadly) never be better than that.
If GOG was given 64 kbps MP3s (for example), then that's what they can give, but for CD rips, FLACs would be nice, even if the difference is only in our heads. :)