I thought that they were in the 86-87db range...
Mr Barnes says in the Sept new that the 3.0 and 4.0 are the same efficiency roughly, and the 3.0 list on the site as 87db
I can tell you that they go LOUD without much power though...
I had them crossed over at 80Hz and powered with 10watt ASL mono blocs and they could get amazingly loud with those small amps-
They are really amazing speakers as well for the $, incredible imaging, I really like them. Augmented with a sub, I was hard pressed to find any deficiencies in comparison to my 9.0's
Dan G.