They're just blabbering, because they know suckers on forums such as this one won't know otherwise.
I have see this to be non accurate, but closean easy way to give you an idea of what an amplifier can produce is by looking at their fuse ratings. multiply it by 10 and you will get a decent idea. if it says it is 1500w and has 80a fuse, then is bs. many dont understand. the true formula is (amps) x ( voltage) x (efficiency) so if your car voltage is at 13.8v and the amp has fuse rating of 100a and efficiency is %85 the best your going to get is 1173w and that would be a excellent amp. lol. because usually your amp will have higher fuse rating than actuall current draw.
My old PDX 1.000 was rated @ 80A Fuse.
Did close to 1200 RMS, (but it did blow fuses when I would crank it)
So I replaced 4 X 20A to 4 X 30A
Also, say an amp like the PA 5500D (rated @ 3200 RMS @ 1 ohm @ 14.4 volt)
Benched @ 2074 RMS @ 1 ohm @ 14.4
Fuse rating = 150A....
