Tangent, I'm sure they measure quite poorly, and look horrible on a 'scope, but does that really matter for audio purposes if you can't hear any difference?
Everyone automatically hates on SMPSes the same way everyone automatically hates on using USB power for anything, and - I strongly suspect - for much the same reasons: a combination of "conventional wisdom", blind prejudice, and the fact that you connect that to a 'scope and crank the resolution up to 1 millivolt and OMG look at that, that's horrible, get it away from my precious audiophile system, yech.
My whole point was that nightanole doesn't appear to even have a PSU yet, but is looking for solutions to a problem that he(?) doesn't even know exists yet (i.e. PSU noise), and which I maintain isn't going to be an issue as long as he(?) doesn't buy the oldest, cheapest SMPS that can be had - assuming the end point is, indeed, to power an amplifier and not draw smooth straight lines on an oscilloscope...
"12-14V 3amp min" plus "power amp" makes me think "chipamp", and I can't think of any power chipamps that have particularly horrible PSRR, etc, off the top of my head. Even the various crazy Gainclone cults have embraced the SMPS as a perfectly workable power source...