@jfg just a heads up it's totally possible to do this with one less actor if you want a slightly tidier plot.
I also changed the volume scale to 0-100 so that it would make more sense to an operator as a percentage, but it's essentially the same as what you did.
It's working fine now, I can now have a control for each individual sound source on each individual scene that I can either control through the on screen faders or by using a midi interface without them conflicting with each other, and the values put in each scene are retained when I leave the scene and then go back. ideal.
My goal of making this intuitive and idiot proof is coming together nicely.
Thanks again I would have been struggling through the brain fog without you.