Perhaps a stupid question but I'm trying to get my head around dynamic range compression of classical music CD's: If JRiver Media player can be trusted most classical tracks seem to have been mastered with a dynamic range of about 15-20 dB. Compared to other music that's certainly very decent. Yet I wonder: it seems to me -totally subjective as not only did I not measure this but obviously the listening environment is totally different- that when enjoying a live classical concert, the range is a lot larger. Is there a set of 'rules' or a validated theory that determine how much compression is optimal for recordings and if so, what are these based on? And if not, apart from potential volume management problems, why not use, say, 40 dB dynamic range? Apples and oranges, I know, but I'd be grateful for any insights.