My 'out of phase' surrounds were definitely out of phase with the rest of the system - not between the 2 of them. I had stupidly wired both of them backwards using the Axiom wall brackets. I reversed the wires & all is OK now.

Perhaps 4 X 5.5" drivers can go lower than advertised in my room especially because they operate in a 12' wide X 3' deep alcove.

FWIW, I found this at AVS Audyssey thread explaining what is supposed to happen if the calibration is going correctly:

*Audyssey has simply 'listened' during the measuring phase and reported the -3dB point of the frequency response to your AVR. What this means is this: when Audyssey sends the test chirps it will measure the frequency response of your speaker and find where it starts to roll off (i.e. become 'less loud'). When Audyssey detects the point at which the frequency response is down by 3dB ('the -3dB point' or 'F3') it stops trying to correct for the in-room response. So if, for example, your speaker is -3dB down at 50Hz, Audyssey will detect that and will only apply the EQ down to 50Hz. Audyssey will not correct below 50Hz for fear of boosting the lower frequencies beyond the capabilities of your speaker and damaging it. (Advanced users may wish to read the Technical Note below).

It is then the responsibility of the AVR manufacturer to decide what to do with that information. In some cases, if the -3dB point is, say, 40Hz, the AVR will set the speakers to Large. In other cases, the same situation will result in the speakers being set to Small with a 40Hz Crossover set in the AVR menus. In addition, Audyssey takes into account the placement of the speakers in the room and the room characteristics itself when evaluating the -3dB point. So if your speakers are in a corner, for example, they will deliver more perceived bass than if they are out in the open because the room reinforces the bass. All of this will influence the Crossover that is actually set.*

TAM