Been banging my head about this. (mainly because I have a pair of Mullard long plates that don't have matched sections) I would like to put the best in the unit of course but I also know that the electrical needs outweigh the sound sometimes (son of an engineer ya know!) Is it necessary to match the two sections? In the manual Mcintosh describe that you don't need to worry about matching but I suspect they were actually talking about the power tube sections and how they work with the 12BH7s... Anybody have a clue as to what is correct for this electrically?