Speaker emitting sound artefact

Hi,

My Sonos Play:5 has started emitting a strange crackling static sound (similar to when a radio is not perfectly tuned in), but it does it both when playing music and when not, so it is not related to the music itself (the only way to kill it is to unplug the power).

What could be the cause for it and how could I fix it (or what type of specialist do I need to see to fix it)?

Here’s a demonstration: https://www.dropbox.com/s/2q0ezwn0ywwlr1...

Any ideas?