The Linkwitz Lab Orion 4
Definitely one of my two best sounds at Axpona, along with the BAT-Scaena room, was the Orion 4 dipole speaker (from $14,750/pair with analog line-level crossover), designed by Siegfried Linkwitz and with custom enclosures made by Wood Artistry. Quad-amped with two Bryston 9B four-channel amplifiers, a Pass Labs preamp, and a Marantz CD player, the "William Tell" section from Shostakovich's Symphony 15 had superb dynamic range, with a "quiet" quality that seemed like there was a lower level of spurious behavior from the room. This allowed a wealth of detail to be perceived even when the music was itself quiet.
Each Orion 4 weighs 85 lbs and uses five SEAS drive-units: two soft-dome tweeters, a magnesium-cone midrange unit, and two long-throw 10" woofers especially developed by SEAS for the open-baffle loading used by Linkwitz. The crossover frequencies are 90Hz and 1440Hz and the tweeters, the midrange unit, and each woofer are driven independently, though the woofers can be paralleled to allow tri-amping if only six amplifier channels are available.