How much Power do speakers really use ???????

Weiserb:
This is antectdotal;guys with physics degrees,please cut me some slack.
The softest sound,at the softest pitch,(a flute)is about 50 decibels. On a music score,that is notated pp. Each time you double the loudness,add 10 decibels. That is p is 60db,mp is 70db,mf is 80db,f is 90db,and ff is 100 db. A modern orchestra with everybody playing as loudly as they can at the same time is 100 decibels. Some rock bands play at 110db.
If your speaker is rated at 8 ohms resitance, count 1,2,4,8,etc. If your speakers is rated at 4 ohms,count 2,4,8,16,etc. If it's rated at 6 ohms,count 1 1/2,3,6,12,etc. Everytime you move up a "Counting step" add three decibel watts.
Say your speaker is rated 90db at 8 ohms. At one meter,the speaker will have a loundness of 90 decibels being fed one watt. At 2 watts,93 db;at 4 watts,96 db;and so forth. At 90 db into 4 ohms,it would be 90db at 2 watts;93db at 4,and so forth.
It's true,as Sean says, that different speakers have different rates of change at different distances,but anecdotaly,I'd allow 6 db'ds of headroom.

Busaganashi:
To double check my facts,I looked up the B&W Nautalis 803s on their web site;they are rated 90db into 8 ohms.
So 90db would require 1 watt,93db-2 watts,96db-4 watts,99db-8 watts,102db-16 watts,105db-32 watts,108db-64 watts,and 111 db-128 watts.
Sounds to me as if 110-120 Clean watts would fill the bill-with headroom to spare.

Ok,I see Sean's point.

None taken,Sean;I enjoy reading your posts,really.