The Viva Audio Nuda horn system knocked my socks off at HiFi Deluxe in Munich this year. I'm still thinking about how it sounded on opera, and what I'll have to do to get my own designs to get there/beat that. I haven't heard the Viva Audio Masterhorn, but if the designer Amadeo is to be believed, and he tells me that the Masterhorn is even better, that might be the horn loudspeaker to beat.
According to Bob Clarke, each pair of Amadeo's "statement" speakers are just a little different as he makes ongoing tweaks