Here's the thing.. That Mack and that Porsche both have close to the same horsepower, and torque.. Look them up you'll see. 2-500 hp with
1-2000 foot lbs of torque.. The difference is the size of the parts.....
Foot lb of torque... BIGGER
Same thing with speakers, it's where the speaker starts to distort not how efficient it is. The E factor is rather arbitrary, IF the distortion is LOW and reproduction is correct, Audiofile or not.... That is my end of the line goal.
If I can reproduce quality sound from 40db to 115db, I'm a pretty happy soul. I don't use my ears either. I've found if you don't run sound test, and collect your own data, your wasting your time..
When I mentioned the 84% speakers, the factory was 89 or 91.. THEY aren't usually accurate, and it's REAL easy to fudge the measurements.
Bigger amp, treat the room... You want to make sure to run some test and see if its running out of gas, and distorting... Pass is not the end all amp it's made out to be.. It is a great amp though.. I like Ampzilla, Serious amp, there. Hook a single 2000, up.. You'll see.. Compare the two..
Wish I would have never sold them...:-( You could have turn them up until your ears bleed, with those speakers... 25 watts is 25 watts plane and simple.
Regards