I may not fully answer your question but if you have the money go for P.Q version as it is a very good value (in term on AN gear) for money as expensive as it seems. When you look at the new double C -core transformer price it is close to $1.5k a pair if bought separately. Count the rest of the parts (BG's and cooper oils silver wire etc) and it looks that it is priced VERY resonably. I'm fooling with AN Quest's (standard with EI cored trans 300 and rather average parts quality) and it easily trounces my DIY all cerafines, Black gates and jensen oil "Flesh & Blood" with lesser (but quite substantial ) output transformers. It is a trivial but often forgotten (also by me ) truth to start with opts and than add exotic parts. Regards, L