Some other things to consider from the “assembler” (VTV, Nord, XTZ etc) -
Does it have XLR, RCA or both types of inputs. By default these units tend to have only XLR, with RCA being an add on. I see your SMSL was RCA.
Is it “always on”, Auto On/Off or Does it have a 12v trigger (useful if connecting the amp to an AVR or Dac with trigger output). If it doesn’t specifically say anything, it’s probably always on. These units have very low no load power consumption, so not the end of the world - but something to be aware of.
Does the unit have adjustable gain settings. This is good for matching the amp with different types of AVR’s, processors or Dacs/preamps. When unmatched, you could end up with the amp either being overdriven (noise/hiss) or underdriven (not enough volume and only being able to use a portion of the amps power).
By default these amps have 26-27dB gain, as opposed to THX standard of 29dB.
if you tell us the “output sensitivity” of your Dac/preamp, and whether that is XLR or RCA that will help. It will be something like “nominal 1 V rms, max 5V rms. The amp should have a closely matching “input sensitivity”. Note that “Gain” is derived from the input sensitivity. So adjustable gain, is really adjustable input sensitivity.
The vendors on my radar are Nord, Apollon, VTV and Audiophonics. Nord is the the most well known, and has a US distribution option. VTV is new in this space, and seems to have the best prices. Now that you’ve determined the module (NC502 MP), I would look at all the vendors, and compare prices (exclude vat, include shipping) for that module along with paying attention to things like the above and then decide the right option.
As indicated in the other post, don’t worry about the upsell for custom input buffers etc. the standard hypex ones are extremely good, and you can add custom ones later if needed. Actually, I think the “xxxMP” modules don’t allow custom input buffers anyway, so may be a moot point.