The Vittora's are excellent - I managed to listen to a pair at Washington D.C.'s Capital Audio Fest in 2013. There's just a tiny hint of horn coloration in the midrange, but other than that they produce wonderfully clear and dynamic sound and are extremely well-built. There's also a matching sub if you need the lowest of frequencies reproduced.
If the sound of horn-loaded speakers aren't to your liking, there are a few high-sensitivity dynamic models as well. I've heard good things about DeVore Fidelity's Orangutan O/96. See http://www.devorefidelity.com/orangutan.html and http://www.stereophile.com/content/devore-fidelity-orangutan-o96-loudspeaker.
Living Voice (based in the UK) also makes a number of high-sensitivity dynamic loudspeakers (~94 dB / W). I listened to the OBX-RW model at the same show driven by a single-ended 300B amp and the results were fantastic. It's amazing what 9 W can do with the right speakers.