I just took up Nick's offer at trying my Prime PSU at his place.

Well his Prime PSU was silent (feintest of hums if I put my ear to the metal case) and mine was not. Even when powered through his AC/AC regenerator (ie better than a DC filter) and > meter+ away.

As others have stated, no reason why my Prime PSU should be not be equally silent. My first one seemed even louder.

Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).