Class D options

I’m looking for a spare pair of monoblock, just in case my tubes fails.
My main options are:
-Mola Mola Kaluga
-Bel Canto REF 600
-Theta Prometheus

They will be driving the mids and highs of my Evolution Acoustics MM3s. My preamp is an ARC Ref. 10.

Thanks for your help.
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But in one review that I’ve read in Sterophile, they were considered to have lesser sound quality than the Prometheus...
So,  you are looking to have something on hand, which you may never listen to?

Make your own.
From everything I’ve read about the Bel Canto/BC Ref600 monos,
they sound like a great product with the NCOREs, which seem to be supporting the higher end Class D amps, and trickle down tech from the BC Black series. 

Im just a BC DAC owner and like their products (I plan to buy a BC Ref 500s amp myself.)
.  But of course, it all depends on speaker synergy....
That’s a great idea Erik, 
I was just on their website last week looking at the Monoblocks.

The moons are so easy to “build”, Just plug in some wires, solder a couple things, and screw the amp case shut. I watched the DIY video. And they have the NCORE modules that I wrote about above that are the latest and greatest affordable Class D tech.
Digital Amplifier Company (DAC) I just had a Stereo Maraschino (STM) on demo and love what it did. Clean and tuneful through the full spectrum of sound with loads of detail that sounded just right on my 100db Charney Audio Maestro's.
Will be purchasing a pair of mono blocks and his preamp when released.  
NAD M22 V2.
I have an M27. Sound is smooth, and detailed.  It soundstages very well. Quite wide though not as deep as others. Bass control is also very good. 
I have the Bel Canto REF 600. They sound really amazing with my Dynaudio Confidence C4's. The review stated it very well. I really like the sound. This is my first Class D AMP and I cannot believe how good they sound.

Another vote for Bel Canto Ref600M. I would steer clear of any UcD Hypex module build amp, especially if you plan to pair them with Ref10.

I have heard Mola Mola Kaluga’s and they are quite amazing. You should also consider Merrill’s Veritas mono’s.
lalitk: What’s your concern about the Ref 10 and the Class D amps in my list? Could you please explain a little more about that? Thanks in advance.
Between the Mola Molas and the Bel Cantos, which one will be giving a more lifelike sound with my Ref 10? I’ve heard that the Mola Mola has no soul.... is that correct?
Merrill Audio is another great option... Tons of online reviews. 
Why not buy a new amp the day after your tube gear fails? Are you far from an urban area or hifi stores? You can also buy all of these items on A'Gon from online dealers. I was considering the Mola and Theta and found a few dealers and private sellers here on A'Gon that sold them online. 

I just bought the Benchmark AHB2 amp and a DAC3L online.  BTW - I went with the AHB2 over the Theta and Mola based only on reviews. 
I suspect much of the issue with the Mola Mola Kalugas is that many reviewers and owners don't give them a chance for break-in.  They are superbly engineered amps but the break-in is supposed to be really severe on some class-D....I have heard to expect changes up to 1500 hours.  
Red Dragon audio monos ... 
+1 Bel Canto REF600M, but you should consider the Bel Canto Black EX amp. What if you like it better than your tube amp?
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