Reducing noise on critical music like classical music is possible, but it's always a question of how far you want to go.
Reducing hiss (I wouldn't go as far as totally removing it, makes things sound a bit 'dead') and noise such as passing cars, coughs, thumbs (like the lady hitting your stand) can all be done. The hardest part is judging how much you can reduce them without doing more bad then good.
Of course, with powerful tools like Cedar, you'll be able to dig deeper then with less advanced tools.
Maybe I can help you out
