[url="http://basschat.co.uk/topic/282884-the-handbox-amplification-thread/"]Handbox R-400 for me[/url], by a country mile.
It's a little bit heavier than you'd like, but it's not actually heavy, and it's compact.
And it's an honest old-school 400w. Remember, amps didn't need to be 500-plus watts. The current ratings are a marketing phenomenon that only came about when the technology changed.
*ducks behind rock*
http://www.youtube.com/watch?v=uLyBAFiJRJY