I again tried to compile rio500-0.8.1, but without success. Compiling fails under kernel 2.4. This is an unresolved issue and mentioned in the discussion forums. So I installed the Rio500 package rio500-0.7-1.i386.rpm. Interestingly I managed via the command line to
a) format the internal memory: rio_format
b) create a folder (which is necessary before one can upload a song): rio_add_folder c) upload mp3s: rio_add_song ). That's a big advantage to the crappy Windows Rioport interface. Next time I try to install the Gnome GUI.
When listening to the first songs on the Rio500 that I transferred under Linux, they appeared very silent. When I encode next time some songs I should try the lame option --scale . However, I don't know what argument to use to get some decent amplification of the sound.