Bob, we would all benefit from your experience. Please post back afterwards. It's not perfect but much better than "normalize". Old time radio (OTR) is another of my hobby interests and you can imagine the different playback volume levels encountered on 70+ year old recordings, especially from amateur tape-to-digital domain. It's all over the map. Mp3Gain does an excellent job of "leveling" them without additional losses or artifacts.

Please let us have your afterthoughts. It is a common problem in mp3 music.