Mike,
a UL interstage tranny as per Kevins schematic (with two separate indipendent windings at the secondary) would wonderfully fit into my new project: a hybrid amp with a differential tube stage and mosfets at the output arranged a la circlotron by electrovoice. I met the builder of such an amp (there is only one in the world) and I had the chance to listen to it ... I do need to build it, it was astonishing (for bass freqs).
Keep us posted.
Ciao
Gianluca
