Is the most efficient speaker the best speaker?

I've heard amazing systems with 3 watt flea amps + Klipshorns

and I've heard amazing systems with 1000 watt monster amps and 83db inefficient Apogees

it's all about synergies but how you get to the sound you like can take multiple paths

It's a synergy thing. I never thought I could get dynamics like my friends Klipshorn system powereed by 3 watt flea SET amps. But then I got a pair if grossly inefficient Apogees powered by a McCormack DNA 500. Yes, I have those dynamics and detail and just awesome sound and imaging that he cannot hoe to achieve with his Klipshorns.

2 polar opposites both aiming at great sound. yes, you can have great sound without super effecient speakers. It's jusy pairing the components necessary to achieve that which is tricky.