Can someone explain db sensitivity?

Note to Herman: A difference of 3 db is twice the power, not twice the loudness. In order to double the loudness you need 10 times the power which is 10db. You need to send twice as much power to the 87 db speaker to achive the same loudness as the 90db speaker.

Ok, Herman - I'm willing to retract my post although I have never seen it explained as you have stated.

So, if I understand what you are saying, you would need 1000 times the power to an 87db speaker to get the same loudness as a 96db speaker? This means it would take a 3000 watt ss amp on an 87db speaker to match the volume of a 3 watt 2A3 tube on the 96db speaker. Is this correct?

Thanks
- A