Tony, firstly welcome to the Forum! You’ll find there are quite a few of us UK mAirList fans here, and we are here to help with any query you have (and we’ve seen quite a few in here over the years!).
If your files are not already ‘normalised,’ I would recommend a great piece of freeware called MP3Gain (http://mp3gain.sourceforge.net/download.php)—which incidentally has a Mac version as well. ;D I won’t waste space describing it here; you can read about it yourself.
Personally, I rip files normalised (with silence removal) using dbPowerAmp Ripper, and then run the files through MP3Gain as well.
Also, if you have MP3s with non-removed silence at start/end because your ripper doesn’t do that, you can use the freeware mp3DirectCut (http://www.mpesch3.de1.cc/mp3dc.html) to remove it. mp3DirectCut is the only tool I know which edits MP3s as MP3s without any decoding or re-encoding; among lots of other fun things it can do.