Any high-efficiency bookshelf spkrs


I'm putting together a second system that will have a low-power tube amp/integrated and bookshelf speakers. Amp may be 15W or less. Any bookshelf speakers that would be a good match? Thanks!
bigamp
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Own the Coincident UHS TRS Signatures they are very detailed and musical. Listened a great deal to the DiCapos and they are also very good, image well. Either is very good.
FWIW the Stingray has a lot of power, much more than the 50 watt rating implies. I had one that drove Maggie 1.6s with ease to moderate levels!
Before spending more $, try to audition the Silverline Audio Minuet ($600/pr list). Like all of Alan's speakers, they are easy to drive with flea-powered amps. I was shocked by the performance of these tiny monitors at HE2007 in NYC.