There are lots of programs for playing MP3 under linux, a few dealing decently with big libraries. But when you start looking for a program that does crossfade well and manage big libraries easily - there is nothing.
Rhythmbox does some crossfade, but crashes when you move manually in the song. Audacious does some crossfade but regularly crashes with crossfade plugin.
The real alternative are AIMP2 or Foobar2000 in Wine. It is quite incredible that you can have good solid crossfade in wine and not natively in Linux.
Maybe people spent too much time on useless Pulseaudio (I have much less issues using only ALSA).