Hmm, I don`t know exactly what NC says, but it`s easy to mix up actual load that every tube "sees" in class A (Raa/2) with composite load lines "model", where "composite" tube substitutes both tubes from PP pair, working in half winding load (1/4Raa). Well, this discussion actually shows that you can`t actually belive in all the books/citations/authorities/"gurus"/profesionals. Have no fear, the "winder" is now allright, Raa/2 is now allowed :-).