What is an AV grade switching power supply?

Linear power supplies are much better .For example, high-end DACs have them and are a key differentiator between the mass market sub $1000 offerings and high-end units.

They are designed for low noise and are often considered quiet since there is no high-frequency switching. They are used anywhere that excellent regulation and/or low ripple is required as well as needing low electromagnetic emissions and excellent transient response.

AV grade? Is that like a black one?

Yes I think an AV grade power supply is one that has better noise filtering on board. Like the IFI stuff as was mentioned.  Switch mode power supplies are notoriously noisy, so for AV use, I would think they put in various filters to quiet the noise so the music or video signal isn't affected.

@jumia

iFi audio IPower X Power Supply