How is this snake oil? It's a power supply. OK it's promoted as 'audio grade', what does that mean? To me audio grade is not a high bar. If you read thru the description, it's meant to class D amps that require split supplies. Whether you have a linear or smps, the output rails have ripple. Linear supplies produce 120Hz. I would argue that ripple on an smps is well beyond the audible range since many are f=100-200kHz. But this one says:
Ripple (noise): 31mV @ 1A, 86mV @ 8A
If this is a supply for a power amp, there isn't much gain - maybe 20 or 30 -- if it couples into the input stage. And if the amplifier's PSRR is any good, the ripple will be rejected. Maybe the high sw freq has components in the audible range but I think you should try it out. Hopefully it's a constant freq switcher, probably is. I would encourage batteryman to try it - and report back
. You don't want to use the large reservoir caps, smps typ have a startup problems if the output caps are too big or they dont limit the current at startup if the ramp is fast. I've been thinking about smps for my own projects.
Edit: one of comments on hifimediy were that it produced a lot of noise, I'm guessing radiated noise. If you have high impedance nodes (input is one), then you'll need to add filtering/ferrite beads. Or put it in a faraday cage. LOL.