You are correct, my Nodes were indeed set to Volume (guess it's my habit).
However the method described of using some hidden drop down seemed really weird to me, because I don't ever remember doing that.
I simply right-click on the Nodes line .. see image below.
I had to sit down in front of it to do it so I remembered, it's just become habit here.
Sorry I wasn't more helpful earlier on. I sometimes move projects between DAWs or locations (which can mean a different version of RB/PT) so I guess it's part of my work flow that once I use Nodes I make sure they are the common Volume Node other DAWs and locations will recognize.
And thanks for the compliment on my testing method. I gave it a little thought on how to most fairly test and not allow a different player/settings to affect the outcome.
Make your sound your own!