Hey guys, I was just thinking about something I heard quite some time ago. If you double your power output, you gain 10dB. For every speaker you add from the same amount of power, you gain 3 dB. So, if you add a second subwoofer the same as the first one you'll gain approx. 13 dB. 10 from doubling power and 3 from another speaker. Can anyone confirm if this is right?