Whenever I morphed CD's to mp3 I found myself frustrated with having to adjust volume constantly from track to track and from CD to CD. Many of the converted tracks also had some distortion.
After a bit of surfing I discovered a freeware utility called MP3Gain ( http://mp3gain.sourceforge.net/ ). When you analyse a folder of mp3's with MP3Gain you will quickly see and hear how the volume was pushed, especially on the more recent CDs.
When I adjusted the gain using MP3Gain, the resultant MP3 tracks seemed to have their quality and clarity restored.
The software claims the following:
'MP3Gain does not just do peak normalization, as many normalizers do. Instead, it does some statistical analysis to determine how loud the file actually sounds to the human ear. Also, the changes MP3Gain makes are completely lossless. There is no quality lost in the change because the program adjusts the mp3 file directly, without decoding and re-encoding.'
I don't profess to understand the technology, but my ears tell me this is a good little program that has made my MP3 listening more enjoyable... especially when I listen to my library on shuffle play!