Did a bit of fiddling about with the stereo today, and as it currently stands using the 2x Sonics 800x setup with an active Crown x-over and pairing up just the JBL 4408 (rolled off at 100Hz) and JBL 15" sub, managed to get to 112dB @ 3 metres for 30 minutes.
It's not bad, but a bit short on wot I was hoping, but then, they're only small speakers.
I'll let it sit at that for a while.
So it's back to my normal 70dB listening levels now and still extremely well balanced and very nice.
Only problem with running my listening 'tests' today was that all the amps and electronics sitting on top of the sub nearly vibrated clean off which I wasn't aware of until much later when adding an attenuator before the x-over.
That would have been a major disaster had it happened.
All in all, a most pleasurable experience.
Anyway, hopefully I've pissed off the building, and I'm sure there'll be a letter from management coming soon enough.
F*kc 'em….