I do find all of this very interesting, and certainly the tube rolling exercise can be fun, exciting, and also down right tiresome at times. I do agree that in any given situation, differences may be there, and it is a sort of “flavoring” of the soup, or as put above, fine tuning.
What I think would be an even more interesting thing, would be a comparison using same equipment of course, of all the new manufactured ECC83 tubes out there. I would be curious what others think without bias. I have done some of this myself lately using my Croft Micro 25 and Series 7 amps. I am trying to kind of wrap my head around it all myself! I will leave my comments out of it for now, as more time to soak is needed....
Holbo TT-Nag 110-Croft phono/Innuos Zen MK2/LinnenberG Telemann DAC-Preamp/LinnenberG Allegro monoblocs/Duevel Venus/LinnenberG Maestro SE-Senn. 660S DH Labs cabling
Croft Series 7 amps, WLM La Scala, Naim Uniti1, Naim Nait XS3, Naim ND5XS2, Guru Junior