When "putting the loud pedal to the metal" I would advise using a much larger amp. You are risking overdriving the amp, and causing damage to the speakers.
Several of my power amps have lights that are supposed to indicate when THD is at 1%. Rest assured that at 100watts, the 4 Pi's will be hitting about 120dB on a ratmeter. Voice coil heating will start to reduce the output be several dB's at max input levels, so striving for those last couple of dB's above 120 will take things into the "blow up and suddenly silence reigns" territory if all you have on tap is a 100 watt amp. This is like running a motorcycle engine at 9,000 rpm, sure, it is designed to turn that fast...but don't claim to be "surprised" when a valve stem separates and drops the head of a valve down into the cylinder.
The dB's from two separate sources will not add up and give you the whole theoretical 6dB gain, that would depend upon how well the two drivers are working in concert, the gain is in practice somewhat less.
During ANY high SPL exposure, your ears have muscles that will tighten up as a protective reaction. Takes a LONG while for them to "normalize". Never make subjective audio decisions after running power tools, concerts, etc...your ears will be "out of calibration" causing things to sound "wrong".
How do the new Pi's sound first thing in the mornings, at 75dB listening levels? Are the interiors finshed, all fiberglass in place, etc? All those braces shown made me think that it would be good to attach some glass "out in the middle" away from the walls where it is more effective. I guess I won't say to "wait till they are broken in", obviously by now they are:)
I was going to write a post extolling the virtues of LOWER powered amps, like the Vintage Pioneers I've been playing with lately...never mind. Jerry, you need to start looking for a 200wpc sand amp, and put a candy dish full of foam ear plugs by your front door:)
Sounds like you guys know how to party...sometimes I think about holding a Rave in my LR, just need the mirror ball and strobe lights,
and...
"threw the carseat into the dumpster and headed off into the night"
Steve Earle
Yeah, the wife might not dig all those "young twinkies" dancing the night away while I spin some tunes:( Youth is wasted on the young. Sam