I actually downloaded your PDF over on HF earlier. Really awesome write up, the mod with the transformer wiring sounds very tempting to do... I think there's a lot of truth to this. From my experience, I look at it this way. If you give 3 winders 3 of the same iron cores, you'll likely have 3 different sounding transformers. Winding methods play an even bigger part than core material in the final sound, it's almost like a secret family recipe of sort. That being said, it's also been my experience that if you gave that same winder another type of core to work on, say permalloy (Ni), the resulting transformer will also sound different than the iron but still have traces of their "house sound". It's like the audio equivalent of an artists signature on two different kinds of paintings. +1 on the Monolith Summits. Ward, and Yves have also been excellent to deal with.