Re: On air compression
>>"And it's particularly jarring when I'm listening to my music collection - the old stuff (Genesis, Yes, Camel, some of the classical stuff) is all mastered at lower apparent volume than the newer stuff. So, on shuffle, I'm either deafened or I can't hear the music properly."
You need a tool such as MP3Gain (there's also some out there for AAC and other such formats). They analyse the loudness of each song and apply ReplayGain to it so that the volume level is consistent (basically by cranking down the volume of newer stuff). Result is that the Beatles sound just as loud as current music. I have it applied to my library and all my songs now sound consistent.
I particularly like MP3Gain against some other tools that apply ReplayGain as it edits the MP3s themselves (losslessly and reversably, it just tweaks the internal MP3 gain headers for each frame) so that it works even on devices/players that don't support ReplayGain ID3 tags.