Have you looked into AudioKinesis' Planetarium Alpha?
Great recommendation! I've heard Duke's Planetarium system and was amazed by the sound coming from those small enclosures (the link you provided shows a Beta version which is larger than the ones I heard which use the same drivers in a smaller enclosure and are currently on his site as the Alpha). They'd be on my short list too. Daedalus would be another good bet for high-sensitivity speakers - outstanding speakers, and beautiful and unique craftsmanship!