Having had good success building FirstWatt F3, F5 and J2 clones, it's time to move on to something with enough balls to drive my main system. My Maggies are pretty inefficient, and they're in a 20' x 30' room with 15' ceilings. The F5 sounds excellent, but only manages background levels. The Maggies are nominally 4 ohms. My Cronus Magnum II (100 wpc) drives them pretty well, but doesn't sound as good as the F5, and lacks a bit of dynamics at higher volumes. This suggests I'd need a boat-load of watts to go singled-ended, and it's not cold enough for that even in Ireland. So the output stage needs to be push-pull, class A, with a boat-load of class AB headroom. I figure it's also time to go off-piste a bit and do my own design. I haven't tried lateral MOSFETs yet, so I've designed both a lateral and vertical output stage which will be housed on a single board. (Moving the power connections will determine which is driven.) I've also designed 3 different front ends: a KISS front end derived from the Pass BA-1 to drive the vertical output stage, a CFA front end vaguely similar to the First Watt F5 to drive the lateral output stage, and a dual-LTP front end derived from a late '70s Hitachi app-note (which was also the basis of the Pioneer M-22) which can drive either output stage. The name originated in the topology being derived from the HPA-1, but it evolved from there and ended up being different. I kept the name because Jam gave me a lot of help on it (as did Pico and Mark and others over on diyAudio).