JT Clark,

I had to reread your post there, but I got it, I think. With a level of 20 watts ( using your figures ) 10db headroom= 20watts X ( 10^10db) = 20 watts * 10=200 watts.

With a 100 watt amp one gets 20 watts X (10 ^ 7 db)=20 X 5.11 = 100 watts ( Approximately ).