What happens to an amp below 2 ohms?

The benefits that some speakers that have low impedance's provide, outweigh the disadvantages of that low impedance. Buy the speakers you like best, then buy an appropriate amp.

They blow up and make a mess!

Buy amp and speakers as a unit...and than after a nice test listen. If you are really after a 2 ohm stable amp, and they are few/farbetween, leave out ALL the 'd' amps with ICE modules. The data sheet says the limit is 2.7 ohms. I'd be inclined to listen to 'em.

I'm not even gonna touch the 'need' for a 2 ohm speaker. What I will say, is that if it were pure resistive, you'd have better luck. Since it isn't, you have to deal with reactance. bad juju. You may get lucky and it won't be too awful, but in more extreme cases of large phse angles (highly capactivie or inductive) you're gonna suck up amp power like you own stock in the power company.

Hi sensitivity would also help, but only so much. Less phase shift would buy you more than a sheerly high sensitivity number. especially if you knew such phase shift peaked at or near the impedance minima.

In general, however, there's no need for such a wacky load.

They heat up and may blow up.Not mine i have ROWLAND 8T a great amp.

For some speakers there is no appropriate amp. As Ralph mentioned previously regarding the effects of low impedance speakers.
"No matter what kind of amplifier you have, if sound quality is your goal, it will be at a disadvantage driving a load like this, even if the amp has the current to do it."
Isn't sound quality everyone's goal?