Do a quick face out at the start of the snare - yeah i know it eats out everthing else too but bare with me here - and almost immediately fade in. Just a few milliseconds of silence, maybe 10 at max depending on the snare. Then do a longer fade in to the decaying snare, ending the fade, eg. return to full volume just when the snare hit goes out.
fuck it i drew a picture but cant upload at all now, somethin with my firewall cant be arsed right now but anyway
Then replace that empty spot with another sound that suits your tune, like a brass hit or a bass stab or whatever. Not perfect but it's something at least.
Or to make a long story short, sidechain it to some other sound.
it can be done by phase inversion...... you would need the instrumental though..... and not just an instrumental recording, it has to be THE instrumental
basically you invert the instrumental, the mix it with the vocal version so its lined up PERFECTLY..... if done right, due to phase cancellation, it should silence the music just leaving anything thats not in the instrumental (like the vocals)
its not easy, and even when you do it right the left over vocal can be pretty poor quality..... but not always..... theres some good accapellas out there made this way
oh some old records have center panned vocals and everything else mixed quite far to the sides. In soundforge channel converter there is an option to "leave center material" but i've never tried that this just popped into my head just now. Also never found anything worth sampling that has mixing like this.