Perhaps carefully place your hand on the two sub speakers to see if they are moving at all or stationary and then if not playing, post a couple of screenshots of your Sonos App system settings to show what the sub is ‘bonded’ to and the music you’re playing/volume etc.

Many thanks Ken for getting back.

Yes, they are moving, but the the sound difference is so marginal.

What is the Sub Mini paired to? What sources are you playing? Have you adjusted any settings?

@Nick2319,

I attached the Sub Mini to a Beam (gen1) and One surrounds in the main bedroom, the difference was instantly noticeable with that setup - to the extent I’m thinking of asking Santa for another, to add to a Sonos Ray and Ones we have in the Kitchen/Dining area. 

I’ve left the sub at its default settings, but have you tried turning up the sub volume in the bonded room settings, or adjusting the EQ - Also consider changing the position of the Sub.. my own preference is to put a sub in a corner and in front of my listening position, rather than behind me, but it’s whatever perhaps sounds best to you, in your room.

Many thanks for the replies.

My main setup is with Sonos one’s in stereo for music. Been Looking at the settings and the sub does work and I am happy. Definitely the sound it is enhanced.

Thank you both for your time.