Would I be better off with one SW, the bigger 115sw,
or two SW, the smaller 112?
Or is mixing stupid? Like one 115 and one 112?
IMO, get the biggest sub you can now, and start saving for the second right away. So your at about 700 for a pair of mediocre subs. Personally if I were looking at spending 700 on bass, I’d start here.
Outlet Special: Blemish in finish. See additional pic. Factory inspected and tested. 5-Year Unconditional Warranty and complete Bill of Rights coverage.
www.svsound.com
And then get a second one shortly thereafter. Subwoofers see the whole of the space , unlike speakers that are more “line of site”. But still, if you aren’t running at the edge of safety, I would take the pc2000 all day long over any Klipsch sub. It has much deeper extension, and it will be more linear, absolutely have more output.
For instance, the 120 you asked about has a FR that starts at 29hz. IMO, that’s waaaay too high for an HT sub. For music it would probably be OK but not movies. And adding. Second 120 won’t buy any extension, just a few dB in output capability.
Bass is an investment, and like@pogre said, but once , cry once.