What happens to an amp below 2 ohms?

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?

Isn't sound quality everyone's goal?

Surprisingly, no. Many audiophile revel in that fact that they can weld with their amp, or drive loads like that, even though there is no sonic benefit whatsoever in doing so.

Depends on the amp and how it was designed. When designing amplifiers, one design criteria is the load that it must be able to drive in a stable manner. This is one of many extensive equations that help determine the values of components in the circuitry. it is not magic. It is designed by calculations and one can determine how stable the amp would be for particular loads. This is basic Electrical Engineering. However, there are compromises for each piece of equipment. First is price point. If price is no object, a competent Engineer can design an amp to drive basically any load and not oscillate or fail. This is why you all see different amps from the same manufacturer. price point design. Good, respectable manufacturers stated specifications are true and accurate. Other's specs are not quite true. But to answer your question, it totally depends on the amp, the design characteristics, such as input impedance, gain, load driving capability, transfer function, phase, stability, heat, power output, voltage, etc. All of these result in equations for the circuit that determine the values of the resistors, capacitors, etc. within the amp. compromise any of these and the characteristics of the amp are changed. If your speakers have load characteristics that drop to 2 ohms or so over frequency, then you must purchase an amp that is stable within that power band at that load. Typically, you are talking about a seriously designed and built amp. This is where you really do get what you pay for.

One reason why some powerful amps have lots of pre-drivers and output drivers sharing the burden.

If you can get your hands on the stability charts of the amp over frequency, load and power range, you will see for yourself how stable the amp is.

enjoy