Will be hard to realize without some kind of preamp to control the volume.
Of the devices you mention, the Sonos Port could be controlled in the app, if you set the output to variable there.
How good that will work/how smooth only a test can show - you must know from your Sonos/BL9 setup!
If you’d use the analog outs of the Samsung (if not available, you must use the headphone out) in order to have volume control.
A turntable normally hasn’t got a volume control.
Connecting these 3 devices (via analog in) would require a switch of some kind.
Not easy!
Personally I’d get a Beomaster 6500/7000 and connect all there - there are several input ports there.....and you can remote control switching between these and the volume of course.
The BL17’s should then be connected via PowerLink.
N.B. If you in this case want wireless, you could connect a Transmitter 1 to the Beomaster/PL and send the sound via WiSA to the 17’s.
Note: there are more options with the Transmitter 1.
Keep on posting - maybe someone else here has a better idea.
MM