GJ - I am more than well aware of blind, double-blind etc., and subconscious influences, so I did all that I could to do as best that I could.
My question was about valve usage, the hifi thing came along with it, for better or worse.
So far as the mic' goes - I will compare the chalk and cheese valves judged by ear (modern Tung-Sol and old Mulard) and go from there, when I have a chance.