Or if you have low sensitivity speakers like me you could build a current source amplifier like the Nelson Pass F4, then drive it with just about any Bottlehead product you like. I'm currently running mine off a Quickie, a Smash or BeePree would work even better, and i know some people drive theirs with a S.E.X. amp too. All depends on your budget really.
The quickie really is a no brainer, cheap, fun, and you can learn a lot from experimenting with it.