Hm, I must have thought wrong. If you already have enough amp power from the start, with headroom, you probably don't need more for EQ.
I just thought of this in light of what was discussed in this thread, #43 and #44:
(see attached picture)
PA has its challenges and you should perhaps not mix PA and home Hifi. Although for home Hifi you can use some PA stuff (I doubt, however, that deiked home Hifi is used in PA). What I mainly think of is the powerful PA amps that power subwoffers for home Hifi use.:) Nobody here is suggesting...
audiosciencereview.com
So EQing is the same as turning up (or down) the volume for a specific part of the frequency range. So if you already have the maximum amount of power the driver can handle, you won't need more than that to EQ. If you add power and then use it to EQ, your driver will bottom out.
So in effect, when you use EQ to add energy in a specific part, you reduce the total available sound volume.
Example:
Say at maximum excursion of the driver, you can play 100dB at 30hz, and you have enough power to do this. And at 100hz your sub can actually play 110dB.
So the roll-off to the sub and capacity of the driver is so that 30hz is 10dB down compared to 100hz. And you want your subwoofer to have more extension. So you fix this by using EQ to increase 30hz by 6dB. Your sub can still only play 100dB at 30hz, and we already established that you have enough power to do so, so that's fine - you have enough power.
But now 30hz is 6dB higher than before in relation to the rest of the frequency range. So if you now play 110dB at 100hz, 30hz will be 106dB, and your driver will die. As a consequence you now have to limit your maximum volume by 6dB to avoid bottoming out at 30hz. Now you can only play 104dB at 100hz, but with the added benefit of more deep bass at that level than before. More deep bass, less maximum volume.