Okay, so the wife went to town, and I had an opportunity to torment the cat and turn it up.
There's no problem at all producing clean peaks at 110 dB SPL (C weighting), from the listening position about 7 feet from the speakers. This is freaking LOUD.
But now I'm hearing the ringing in the deep bass that I did not hear with my Advents or during the REW sweeps, and I think the speaker location is coupling with modes in the room in ways the old location, flawed though it was, did not. I have some work to do. The speakers are about two feet out from the windows behind them, though the low ports are below the sill by a bit and that distance is more like 20 inches to the wall below the sill. The right speaker is right in front of a floor vent, and I'm probably coupling with an air column in the vent, though the air handler was blowing air during my test. A pillow against the wall behind the port? Closer to the wall? A diverter to aim the sound up (because I can't block the vent)? I already have stuff sitting on the floor behind the speakers, but below the level of the port.
During the test, air was pumping aggressively through those ports, but I heard no port chuffing.
I played a Canadian Brass CD, which is really a joint effort with brass players from the New York Phil and from the Philadelphia Orchestra. This is one of my go-to test CD's for evaluating "reference" volume levels. Playing along on my F tuba had no effect on the SPL meter--I could not play louder than what was coming out of the speakers, at least with the tuba pointed up (as it usually is). This absolutely serves my use case of being able to play along with recordings, and by a healthy margin.
Rick Wakeman's
Red Planet has some very deep synthesizer work in it, and I could feel it through the floor. I could see excursion on the woofers easily in the 10mm range, with the average level sitting right around 100 dB. That new album is more compressed than old stuff.
Emerson, Lake & Palmer's
Trilogy starts with
The Endless Enigma, and there is a spot where Carl Palmer plays a bass drum roll---thump, thump, thump, thump! On the Advents at high volume, this is tight and solid, on the F12's, there is more ringing. I will think about how one might tighten that up a bit. But I was playing this at peaks of 108-110 dB SPL, so it was really a torture test. Maybe it was my brain rattling.
I can turn up the preamp to a higher setting than with the Advents, too, without the sound being scary (other than being LOUD). The Advents would start to scare me--just that hint of distortion that says, NO MORE. I never had that sense with these.
These are rated for a 200-watt amp (nominal, which probably means rated into 8 ohms). I'm bi-amping, but still using the passive crossover network in the speaker, with two 125-wpc amps that sport a couple of dB headroom above that. It seems to be a good match.
Now, my tinnitus is in full flare.
No more testing like that for a while!
Rick "comments welcome" Denney