Thanks for the replies.
Deadbeef and gogglesmm don't seem to deliver what I seek (or I haven't found it).
There is a crossfade-plugin for xmms and audacious, that I can compile against xmms
but not against audacious-2.3
Anyway I am looking for a musicplayer with a good media database
(forgot to mention that in my first post), so xmms and audacious are both out of question.
At least there is a request for this feature for mpd
http://musicpd.org/mantis/view.php?id=1515.
So maybe I just have to wait a little bit and as long as that I stick to amarok-1.4.10.