So I dove in and bought my first Sonos product this year and in July I picked up my Five. I have loved this speaker these past 3 months, but recently a couple of songs I’ve been listening to, I have noticed a rattling type sound, and I think it’s with certain bass frequencies. The rattle is like the casing/ housing is shaking. 
On my five, I use a flat EQ, all zeroes, I have setup the Trueplay and I prefer Loudness on.

the 2 sounds I’ve noticed it on are:

Deftones - Passenger (Mike Shinoda Remix)

Kalley - Alabaster Heart

both through the Spotify service, selected through the Sonos V2 app.

Also I don’t usually get higher than 50% on the volume, and I use the speaker alone in the horizontal position.

Anybody have a similar experience, or have suggestions to change settings? Is the thing damaged/ can it be fixed?

Really hope to fix this issue, since I have already ordered my next product, a Sonos refurbished Playbar is on the way from Beat Buy.