For less that 100 bucks I put in that Sony NWZ 385 Mp3 player and so far I've loaded 51 CD's on it and the sound is incredible, much better than listening to the FM. You can turn it up high enough to blow you off the bike. I can listen to music at 80 mph without any problem at all. It all really depends on your listening ability though, ears are kind of an important factor in this endeavor. My old ear, after listening to diesel engines for 36 years are definitely not 100%, I have to turn up everything louder than my family likes it.
So if its loud to me then its probably pretty loud to someone with excellent hearing. JMHO