Thanks a lot for all your replies!!
You guys brought some light in my confusion....
The intention of my question was the following;
I got a pair 2405 ( labeled 16ohm , Alnico ) and a pair 2440 ( labeled 16ohm ) mounted to a 2390 horn/lense....
JBL claims the 2405 to be
105db/1w and the 2440 mounted to the 2390 to be
107db/1w. Due to the fact that I personally hate the sound of resistors in a passive crossover, I was wondering if these two drivers would match in terms of loudness when connected to the same amp-channel....
I apprehend the midrange will be a little too loud....
So my idea was to swap the 16ohm Alnico-2405 against an 8ohm Ferrit-2405.... Due to the lower impedance the 2405-8ohm should receive more power from the amp than the 2440-16ohm and compensate the lower efficiency....
But I am on the wrong track, ain`t I ?