As far as I know, a good remaster works with the original multitracks. Some tracks needs to be changed and others not. Doing a remaster with a simple computer without the original multitracks, in my humble opinion, is a disaster because you change everything (voice, guitar, drums, etc, etc).
And, of course, you need to hear the result in a good high-end music player. Doing a remaster hearing the result with the computer speakers...
Sadly, sometimes people don't want a proper remaster. They only want a louder version (do you remember the loudness war?)