A little late, but that's because Swiss Audio is slow in responding to e-mails.
SPL (sensitivity) = 112+10*log(9.64*10^(-10)*Fs^3*(Vas/Qes))
For your subwoofer, the Swiss Audio SPL1291;
Fs = 35hz
Vas = 50.7L
Qes = .51
I'll leave the math up to you as I don't want to spoil anyone's fun, but just an FYI, you're subwoofer's true sensitivity is far less than 92.5db //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif Infact, it's not even 88.5db //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif That's more than 4db less than your "personal minimum standard".
Brings things into light when you take the time to read past the marketing BS, and actually do the calculations.