This is Bach's famous Organ Trio # 3.  It is intended for three 
equal voices which were set at one volume for the duration of each 
of the three movements.  For this reason, any  instrument capable of 
the note range of each voice can be assigned.  For instance, bassoon 
to the lowest or pedal part,  clarinet to the middle, and flute or 
oboe to the top.   Of course, I sequenced it to play on the Allan 
Digital Organ which has some excellent sounding Baroque stops.