(Sorry - couldn't resist.) I've been casually looking at heads to replace my G-K 400RB. I want something small and light, and 400W~600W into 4 ohms. I really like the new Mesa Walkabout, but I don't think 250W will cut it for me with a pair of Bag End S15-Ds. (I'll be picking up another Bag End before the amp.) I would also consider a pre/power amp setup. Any suggestions on small, high powered heads that won't break my early-middle-aged back? What about some of the exotics - Glocken(mumble), Walter Woods and the like? Remember, full size racks look silly on top of Bag Ends - kinda like a Great Dane humping a Poodle.