Efficiency will be around 85~86db/2.83v.
Hard to get much more with a small, wide bandwidth loudspeaker.
We choose “system efficiency” over “speaker efficiency”.
For example, a pair of 96db efficient speakers being driven by a 3.5 watt SET amp will have a maximum output 99db and draw about 250 watts.
A pair of 85db efficient speakers powered by our C•100S will have a max output of 105db, with wider bandwidth, better dynamics, and draw only 240 watts.