Here are a few good choices for hi-effeciency speakers.
Reference 3A MM De Capo- easy to drive with SET, but 8-10 watts would be a better match than 2-3 watts.
Galante Rapsody- Great reviews, but expensive considering how similar the are to the Adire HE10.1
Adire HE10.1- as little as $299 in kit form, but more like $1200 if you have the signature version professionally built.
Triangle-all Triangle speakers are easy to drive. Will work with almost any SET, but 8-10 watts would be better.
Cain & Cain Abby-Specifically designed for low-powered amps, the Abbys are a single drive unit. Looks way cool.
Omega Speakers- Single drive monitors
Loth X- high effeciency monitors
Moth Cicada-Art Deco looks, single Fostex drive.
The Ref. 3A De Capo is a great speaker with more bass than any other easy-to-drive monitor that I have ever heard. This speaker will kill many floor-standers in the bass department and is a very smooth and articulate speaker. I highly recommend it if you have enough power.
Enjoy,
TIC