New Atom Looses Power Up & Power Down Click?

I've had many, many issues with my original Atom since receiving to after on release date. 5-6 months in and numerous calls, e-mails etc including rebuilding my home network, my Dealer and Naim agreed to swap the unit for a new one.

Within 10 minutes it was up and running, no hanging, rebooting etc. 

I then noticed that the original unit had quite a loud clicking noise when powered up or down, at first irritating and felt pointless, yet the new one is completely silent. Anyone else experienced this?

Upside, brand new unit - down side, sounds awful at the moment - run in time again!