I found out last weekend by playing CD's at the break of a stageplay can badly expose the public to wide volume variety...
The CD I got from the director started rather soft, but the third or fourth song was too loud. Of course, I only found out when I was not at the mixing desk, so I had to run to turn the volume off. What I did next was rerouting the CD-player into the Audio-interface's input and receiving the audio stream from this input into a separate track in my audio software. Then I applied some compression using a realtime plugin effect (e.g. compressor, limiter). This equalizes the volume peaks, so the soft spots are boosted and the loud regions get smoothed out. Overall, the sound is more even, though lacks some dynamics.