What happens to an amp below 2 ohms?

Rleff, its a matter of power- in some rooms you have enough power with MA-1s on the big Sound Labs and in some rooms you simply need more. But you would not need ZEROs in any event.

Bombaywalla, the word was 'phrase', not 'phase'...

Phase is simply put, Power Factor. Another measure of reactance.
The larger the phase angle, the less power delivered to the load. A 1000 watt amp trying to drive a load which has a 90` phase angle will deliver exactly ZERO power at that frequency. cosine 90=0
A speaker which is a difficult load would, IMO, have large phase angles at the same frequencies where impedance dips occur. A double whammy.
My panels? Not a bad load, at all. low impedance, to be sure, but no wacky phase angles to suck up amp power.

Thanks Ralph;great review on the Ma2's !!!