That M27 looks like a fantastic piece.
The Hypex amp modules are basically as good as class D gets (Icepower ASX2 is also up there; Abletec's stuff is on paper as well, but I've never played with one). The key phrase with Class D is "load invariant." Basically, any module that's load invariant has a chance of being great, because its frequency response will not change with the driven load. Common class D amps (all of them I know of except for the above three) act bad like tube amps. Their frequency response depends on the impedance curve of the driven loudspeaker. (Stereophile's "Kantor load" measurement shows these problems well.)
Obviously, only load-invariant class D amps are legitimately high fidelity devices. The common ones can be used just fine in designs that take their flaws into account, such as an active loudspeaker voiced using measurements of that particular driver/amp/cabinet. But for speakers, they're basically just inexpensive and more powerful triodes. A low fidelity, high coloration, solution.
As for the price, look at how much Hypex NC400 modules and matching SMPS cost on their own, and keep in mind you also get a nice case, 12V trigger circuitry (presumably, haven't seen the back), etc. Sure, the module is "different," but whatever.
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