When I looked at dependencies in gslapt for Amarok and Rhythmbox, there were none listed. So I uninstalled both apps and then reinstalled them. After that the dependencies showed. I don't understand what the problem was before; I'm sure I installed one if not both from gslapt before. Could it be that I didn't reload sources before installing?
At any rate, both programs now start up, although Rhythmbox doesn't work so well. First it doesn't load Jamendo, Magnitune or Cover Art plugins. Second, there seems to be a 5 second delay before it plays anything. Initially, it wouldn't play mp3's or mp4's either, but I changed the gstreamer plugins (with gslapt) from those with vl60 suffixes to those with gsb suffixes. Any idea why these problems with Rhythmbox?