I know 2 subs over 1 sub with the same amp gives a +3dB gain. Is it generally true that a ported box (tuned to specs) gives a +3dB gain over a sealed box?
If this is so, then will one 12" sub in a ported box be equally as loud as two 12" subs in a sealed box, if the same amp is used in each case???
Also what does doubling the amp power yield in a dB gain?