There are people who use their's in a very quiet environment and not notice the problem. But I noticed this in day one and have been searching for a solution to no avil!! Any volume set to 1/2 or less is basically not audible. Even my mobile phone can play louder mp3s!
The internal speakers sounds good for a laptop but volume is way too low when set to max. I also notice it resets the headphone volume to mid when you jack in. Given the output is so low, I almost thought my external AMP was not working!
Anyway, the speakers can pump significantly more volume. I'm listening to Keane - Under The Iron Sea, in iTunes, ripped from my own CD. Volume is fine at max, but the speakers can handle much more volume by giving it pre-amp gain in equaliser. Disable the pre-amp, lower the master volume to 1/2, quiet room, can't even hear the singer. So there you go, it is a stupid software limitation in either the firmware or OSX.
I've seen enough references to weak speakers on various sites/forums to know this is a WELL DOCUMENTED problem! Apple, please fix it! What is the point of having 1/2 of the volume bar at virtually inaudible levels? It is clear to me that a new setting can re-map a new lowest level to around 35% of current seting (6/16 bars), while a new max level is more appropiate at around 150% of current max.