I'm very happy with my single-driver Omega Super 3i Monitors. Fantastic speakers at their price-point. Efficiency is 94.5 dB at 8 ohms and they're mated right now with an inexpensive Chi-fi (3.5 wpc) SET integrated. A Decware SE84UFO (2 wpc) is in my immediate future.
Have Zu Definition IV, and with the right electronics [tubes] they make music. Will say that with any hi-eff speakers you have to clean up the AC a bit. Actually, I'm in love with them but hate to do the fanboy thing.