What Class D amps will drive a 2 ohm load

We finally got him to install a pair of ZERO

This is just trying to save face.

Of course you did, an expensive band-aid fix, that will never get the best from the Alexia, instead of pointing him in the right direction for the right amp even at the cost of maybe an OTL sale.

This Wilson Alexia "customer", was sold totally wrong amp for these speakers that have a pig of a load. That with the right amp eg: Gryphon Antilion and similar current pushing demons, will make them sing at all levels.

I know as my friend Edgar Kramer owner of Soundstage Australia, owns a pair, and we’ve tried many amps on them, believe me "NO OTL" will drive them anywhere near their full potential, even with a Zero autoformer.
https://www.soundstageaustralia.com/index.php/reviews/84-wilson-audio-specialties-alexia-series-2-loudspeakers

John Atkinson Stereophile Test
This speaker will play loudly with just a few watts. However, it demands quite a lot of current from the partnering amplifier.

HiFi News Lab Report
The impedance and phase angles falls to a scary 0.9ohm!! in the lower bass

Now back on topic to the OP’s problem of driving his Thiel CS5’s which maybe an even worse/similar load as these Wilson Alexia’s.

"Here's a thought!! maybe the OP needs some OTL’s"???????????

@georgehifi , 
Can you just drop down the level of sarcasm and argumentativeness a couple of notches?

Bob

George who holds up the Levinson ML2 as the paragon of excellence for technical specs.

This Stereophile’s JA’s statement, is the typical case where a 25w amp like the ML2’s with doubling capable wattage current will drive a pig of a load like these Alexia’s and the OP’s speaker "to a given level" with perfection better than any 3000w class-d can.

John Atkinson Stereophile Test
This speaker will play loudly with just a few watts. However, it demands quite a lot of current from the partnering amplifier.

@georgehifi ,
Can you just drop down the level of sarcasm and argumentativeness a couple of notches?

Bob

 I would if it wasn't warranted, and usually do.