reverse envelope follower ?

cool patch! seems to work well enough for me. It sounds like, in part what you're doing is some side chain compression (with just a 1:1 ratio). There's an example in Max called komp.maxpat that takes an external "key" input in the rightmost inlet. What this would do is whenever the komp patch receives signal in the key input, it will engage the compressor on the signal running through it. You should be able to just lower the volume without actually changing the dynamics. Not sure if this is exactly what you're looking for, it just came to mind after looking at your patch.