Hi Bevan,

What you want is an 'inverted voice killer'.
Voice killers eliminate the singer(s) and keep the music.
They operate this way :
The 'source' HAS to be a stereo recording and the best(lead) singers' position in the panorama is MIDDLE.
By inverting the electrical 'phase' of the L and R channel the result of those signals that exist in both L+R is almost nihil.
This action combined with a filter that passes non-vocal frequencies creates a 'new' MONO (!)recording in which the vocals are reduced.
Unfortunately many other signals are reduced too and the quality is poor.

I think there is no 'standard' tool/equipment that answers your demands.
In CoolEdit you can create your own 'filters'...... good luck !

Roel