Just got me thinking of LADSPA sequencers... Can you open files in a LADSPA plugin?
I don't know if this is even remotely feasable, but I remember a tracker from ages ago (I can't remember if it was in linux, could have been dos) that was entirely command line driven and just read plain text files for the tracker sequences. A LADSPA tracker may be stretching the "simple" factor slightly, but it would be a fun project (and ahem, SSM needs a tracker badly!) dave