Good afternoon,

I remember many years ago a publishing project with
a marching band percussion feature where the company was able to
set it up so you could adjust the balance knob on your stereo and
hear the snares, tenors, bass drums, individually.  Is anyone
familiar with how that is done?  Software? 

Can you take an mp3 of a Sibelius file using Virtual Drumline instruments,
say 3, and separate them using a stereo knob/whatever of some sort?

I look forward to hearing from you.

Take care,
Neal

can you provide a link?  What you're asking seems impossible on a standard home stereo.

The only thing a balance knob can do is isolate L and R speakers, so you would put an instrument mostly to the left or right in the Kontakt player.  Of course, it doesn't sound very good when evenly balanced.  If you wanted to isolate 4 instruments, it would have to be in surround sound on a surround-capable system with adjustment to each channel.