I also find it odd that it would appear the subs are 5 db hot vs the mains (given they register 72/73db on a C weighted Galazy CM140 vs 75db for the mains using the AVR's test tones).
I then plopped in 5 of my favorite scenes for bass and used the A-B function on the Oppo BD83 to play the same few seconds over and over. Pulse (played from just before she opens the door to a few seconds after she walks in). WOTW, from when Tom Cruise picks up the rock to where the crack in the pavement moves up to the building). FOTP, from approx. when the plane starts to break up for say 10 seconds (the most demanding part I found), the Gunshot scene in Open Range (literally, just where Costner pulls out his gun and blows away Kim Coates), and finally House of Flying Daggers where the princess reponds to the "third" bean thrown at the drums.
It's funny, because I went back and read the comments about "never having experienced this kind of bass before in my room". Well, it's possible I simply forgot how good the PB13 is.
With Pulse (listened to this at -4db to ref), played the scene some 5 times for each sub. It was next to impossible to tell the difference. At times I thought maybe I heard some port chuffing from the PB13, but then played it again and wasn't sure. Overall SQ? Really difficult to tell the difference.
WOTW - in this scene I pumped up the volume to -1 to reference. To me the PB13 seemed to have some more "feel/sound" to it. Again, SQ was very similar, but there were points in the scene where the PB13 felt a bit more visceral.
FOTP - Wow, both systems rocked this scene at -1, painfully to my ears. The AV15Hs seemed to add more "texture" to when the plane was turning hard, but this could be personal bias as it was that close.
Gunshot - The gun shot simply slammed my chest/head way more with the PB13. But I definitely noticed chuffing (and felt the air from 14 feet back of the sub!). Found that interesting, and wondered how much of it was due to the advantage above 70hz? Not sure where the gun shot scene resides.
Flying Daggers - again, the PB13 seemed to offer more output on this one. But the "sound" from the AV15H's with the drums was somewhat more pleasing to my ears.
I haven't listened to music yet.
I then replayed the scenes about three times each (same A-B few seconds each), and did the crude "what does my SPL meter register as max" test, and the "max" results were repeatable within 0.5 dbs.
AV15Hs vs PB13
97.9 vs 98.4
97 to 102.3 (wow!?)
118.3 vs 117.8
105.3 vs 108.6
102.5 vs 107.4 (wow again!).
Looking at the above, I'd have to say that down low the PB13 is outplaying the AV15Hs, and in some cases by a wide margin, and somewhat agreed with what I thought I was feeling/hearing with each scene before pulling out the SPL meter.
As for SQ, I'd give a slight edge to the AV15Hs, as I did hear some chuffing at near reference levels from the single PB13 but I'd imagine that advantage would disappear with dual PB13's. But honestly, I could go either way and rarely listen at reference levels so the chuffing would likely go away or reduce considerably.
I almost hated to post the above, because I really wanted the AV15Hs to demolish the PB13. It could simply be how I've setup the subs (maybe I've got something wrong), but the PB13 in terms of output was matching or GREATLY exceeding the DUAL AV15Hs (4 woofers, two boxes, 1700 watts or so per side) in most cases.
Of course, I couldn't calculate distortion at all, and maybe the PB13 was distorting more than the AV15Hs, but honestly, if it was, I didn't notice.
Wow. I'm somewhat disappointed! Not that I'm displeased with my subs, but I really really wanted them to shine more than they did. The PB13 is a monster of a sub, I always knew it, but didn't expect it to keep up to duals.