My main gripe about MP3s isn't the format itself but the inevitable huge difference in recording and mastering levels plus dynamics when converting old and new

My main gripe about MP3s isn't the format itself but the inevitable huge difference in recording and mastering levels plus dynamics when converting old and new material for use on the same device such as for example portable media players. I've partially solved this by re-encoding everything that I put in there (1) using a macro on Audacity (suggestions on different tools welcome), however it sometimes crashes on some files, no reasons given why, and the result isn't what I would require anyway. All other methods (replaygain) fail or don't fully work. The problem is due to the difference in level and dynamics: older material is either slightly compressed (analog master, vinyl or tape rip, etc.) or less compressed (digital remaster, CD rip) but still and very low in average sound level; newer material however is being over compressed to make it sound louder (search for "loudness war"), therefore to reduce all music on the same player to similar levels a tool should operate on dynamics first, taking account of the different ratios of the material being given, then once the dynamics has been normalized, it brings the volume to the same level. As far as I know, there's nothing out there that does anything similar. (1) Yes, I know re-encoding is THE bad thing, but that material isn't going to leave that device.