Yep, single driver designs with high efficiency is one of the best speaker to couple with SE tube amps. But they're not without their challenges such as limited frequency range - especially bass, exaggerated midrange, and colored response.
After years of owning at pair of very nice single driver speakers I've converted (added an ambience tweeters and subwoofer). If I were going the route I'd start out by looking for a nice/efficient 2-way and realize that SE means being limited to small ensemble music in a small room or possibly a huge/high efficiency speaker.