I'm a tuber; slap me. My preferred power amp topology happens to be the circlotron (bridge) connection, with the tubes biased into class AB. My homebrew monoblocs use four EL34, or KT88's in the larger version (2 paralleled pairs) with 2 floating plate supplies in a bridge arrangement. Two smaller floating screen supplies are also required & deployed. Basically all 4 tubes are in parallel across the transformer primary. That allows me to have a lower turns ratio which can result in a better-performing transformer, which uses a so-called multi-filar winding technique, in which a ribbon of a number of wires is wound onto the core, and some wires in the ribbon become primary, while others become secondary. The selection of which wires in the ribbon are in which winding is the subject of a patent on this transformer. The resulting amplifier has low distortion and does not goop the tube sound on everything. Negative and positive feedback are used. Positive feedback comes from bootstrapping the driver stage. They tickle my nun-handles just fine.