One thing that is complicating my decision is the amplifier specs for some of the subs.
The amp in my Sub 12 is said to have a 1,700 watt amp (3,600 watt peak) and I'm running it along with all of my other gear on the same room circuit. I've had no issues. That said, I also know that I don't listen at levels that will max it out. I don't expect that my listening habits will change with a new sub. Like I said, I'm mainly looking for more extension. More thump won't hurt, but I'm not looking to rattle dishes out of the cupboards upstairs, LOL.
So when I look at a sub like the Defiance 15, it's rated at 900 watts (1,800 peak), so I know it should be no problem at all. Less powerful than my current sub. Same situation as something like the PSA V1510 or V1811 which is rated at 960 watts (2,100 peak). If I look at something like the SVS PB-4000, it's showing 1,200 watts (5,000 peak).
At what point are guys running dedicated lines for their subs? When running duals or more? Those PSA subs look very interesting, especially the V1811 which actually has a smaller footprint than the Defiance 15. I almost have to wonder if I'd be using less power to move a big woofer in a ported box to levels that are acceptable in room, than I am asking a 12 inch driver in a sealed box to do the same. I can't imagine ever needing more than a single given my room size, and if I'm going to do it, I may as well do it right and find a sub that will last me years without wondering if I made the right choice.
So much to consider!