Yo, back on Tuesday 20 April 2010 Ken Restivo was all like:
Kind of a general mastering question, but obligatory
Linux screenshots of JAPA are included, I promise.
I've noticed with some professional cd's/oggs/mp3s I have, the high end is rolled
off at around 20Khz.
What makes you think that is due to mastering? Consider the fact that most mics freq
response begins to roll off between 16k and 18k...
-Reuben