The best small bookshelf speaker you ever heard?

always liked the Proac Response 2

Renaissance Piccolo

I remembered contributing to a similar thread here a couple years ago.

Tidal Amea (still awaiting an opportunity to hear the Amea Diacera which is mor than likely even better).
http://www.tidal-audio.de/english/amea1.htm

In the very compact category (12x6x9), Kiso HB1 by guitar and violin builder Takamine leaps to my mind.
http://www.kisoacoustic.com/introduction.html

Always provided, of course, one does not actually put any of these gems on bookshelves, which probably goes for all or most of the previously mentioned as well!

For me, small speakers are a "pick your poison" proposition.

If you want octave to octave balance (my #1 priority), you have to sacrifice bandwidth at both ends or accuracy (or both). A little mid-bass hump, while inaccurate, restores balance. IME, if you want real accuracy through an extended top end, the speakers will cry out for a sub.

That said, the (original) Red Rose Ribbon monitor (ribbon extends above the front baffle), while somewhat colored, is really satisfying as a stand alone monitor. The old Sonus Faber Minuetto is another speaker that made a similar trade-off. I own, and still use both.

Marty