This thread treats amateur vs. pro as a binary equation and it isn't even close to that. Every category possible has a range of genius to idiot and music engineers are no different. Two easy assumptions here would be that a genius pro is better that a genius amateur and a genius amateur is better that a professional idiot. 2 words about each you could use to tell the whole story would be speed & consistency and trial & error. So, if you have time would the amateur be able to do a project as well as a professional? Eventually, it's possible. On EVERY project? Nope, unless of course you've done it enough that you're on your way to becoming a professional... which is usually how professionals are born.