Class D

Certain Class D amps thrive, others not so much.  AVM and Rogue I know from personal experience are fine and more than stable at these lower impedances.

Other brands I know struggle a bit.  

Some class D amps can have problems with more difficult speaker loads, but it's hard to know without trying if the manufacturer isn't saying.

I use Hypex, Ice and Behringer. ALL will push 1 ohm loads.

I don't like the sound of ICE or Behringer for anything other than BASS.
Both the 2K ice and the 12K Behringers, are PURE workhorses. I use them for what they are intended for. I use 3 12K double amp modules when we want a little THUMP for a block or two... Still cooling down from New Years. LOL

Hypex on the other hand.. Night and day to me.. I use Nords with revision D buffers..and NC500 modules. I opted for 2590 sparko pros for the opamps. I've used a LOT of different opamps through the years.. THAT one is a real keeper. My speakers are wired at 3.1 ohm. Small planars.

They did dip to under 2 ohms, before I split the circuit. 1.7ohms in the bass region..

I went to pure class D on the bass and Valves from 300hz and up.. I've NEVER looked back.. 5 years now..

I did some mods to the Behringers. I put HQ toggles on the PS fan and disconnect the other two and put them on a thermal ONLY switch. LOL They came on New years for the first time.. 8 12" UM, 4 15" UM and 2 18" UM. Ultimax Daytons 2496 Active XOs

About 100 CF of cabinets.. BOOM BOOM...VERY well behaved...

100+ db for over an hour.. We didn't need fire works.. KIDS..

Summer it's all class d for 3-4 months, come fall winter and spring, Class ds and Valves...Just a match made in heaven.. I'm pretty picky..

I don't care WHO makes it, I'll figure out if its worth a hoot. right app goes a long ways...

Regards...

zappas
Most that I see are not rated at 2 ohms.

Because there’s a reason for that they don’t fair well or shut down. Be careful with your choice

Look for independent bench tests, like this Stereophile one.

Your PSB Stratus gold need an amp that breeze through very low "EPDR" (combined impedance/-phase angle) in the bass 50hz-100hz, also low impedance in the mid bass. 
https://www.stereophile.com/images/archivesart/PSB97FIG1.jpg

Look for amps that can come "close" to doubling their 4ohm wattage into 2ohms (eg: 4ohm-200w/2ohm-400w) this means they have no problems with current into 2ohms.

Stereophile: Its impedance curve (fig.1) also suggested that it needs to be partnered by an amplifier capable of a healthy current delivery. Not only does the impedance drop to a low 2.72 ohms at 97Hz, but the -phase angle is quite severe through the midbass region.

Cheers George