I've never done this using software compressors. Only with an outboard unit, years ago. And I barely remember how I did it then. I know it has something to do with a sidechain, but thats as far as I'm aware. I'd like to set it up so my existing stereo guitar track drops out ever so slightly when the vocals are present. I have two stereo tracks. One is a mixdown of my guitars and the other is the vocal track. Thank you in advance for your help!