When I crank iTunes and the OS volume up all the way and start a song, it starts playing at maximum volume for about the first 5 seconds, before becoming a little bit quieter. Basically feels like it cannot play at sustained maximum volume and has a limiter at about 80%. Pausing the song and pressing play again gives me another short 5 second burst of beautiful maximum volume before reverting to a quieter level. The volume sliders do not change, indicating it is still playing at max volume, but there is a noticeable reduction. Anyone else getting this? Apple Support is clueless of course.