EDIT: Damnit, boomana, you beat me to it. I do think that "hella powerful" is not necessarily a good match with all speakers. But based on your description of what you say you like, and based on my understanding of things, I'd say go hella powerful. I like hella powerful, myself (got a Musical Fidelity A308, myself). I would also add "monoblocks" to your thinking, especially if you're into soundstage/separation. (Both my MF and my Manley Stingray are "dual monoblock" designs.)
What I don't understand is why you're going custom. There are some mighty fine amps out there that will suit your needs (I think), well within the <US$10K mark.
I'm not saying "don't", I'm just trying to understand better.
Oh, and ... tubes? SS? Digital?